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Joshua and Margaret
Joshua and Margaret are the parents of Jake and Jermaine, and the adoptive parents of Finn. Finn loves his foster parents very much and treasures Margaret's music box, as seen in "Jake vs. Me-Mow" that she used for lullabies and carries it with him in his backpack; he sees himself as their son and fellow 'puppy.' Finn also describes that his adoptive parents did a good job of raising him, as she described Margaret raising him 'graceful' in "Jake Suit."
As housemates, brothers (adoptive) and best friends (homies), Finn and Jake share a very deep and strong bond. Having been raised together by Jake's parents, the duo share a relationship similar to that of siblings, with Jake acting as Finn's older brother. One unique part of Finn's relationship with Jake is Jake's ability to tell when Finn is about to cry, as seen in the episode "Freak City" where it is stated to be a "mother-daughter thing."
Though they have an unconditional love for each other, Finn can get frustrated with Jake because of his laziness and lack of motivation, as seen in many episodes like "The Witch's Garden." As a more laid-back character, Jake often tries to relax Finn's fiery personality in the face of a struggle, frequently advising him not to worry. While he sometimes leads Finn down the wrong path, Jake genuinely means well for his companion and is usually an encouraging and protective figure in Finn's life. In "Incendium," Jake ventures out to find a girlfriend for Finn to fall in love with, implying that he tries to help Finn in his problems. Finn and Jake have saved each other's lives on several occasions, and often adventure throughout the Land of Ooo together.
In "Dungeon," they both try to survive throughout the dungeon trials; however, they both fail at it and they realize that they need each other as a team to solve their problems, too. This is also evidenced in "Who Would Win," in which Finn says he wants to have an award with Jake, instead of only himself.
However, there are some occasions in which Finn and Jake fight each other. In "Video Makers," they argue on what genre their movie should be, and they refuse to talk to each other until BMO fixes the problem. In the end, they always come back together to being friends. In "Who Would Win," their fighting goes to a higher level, since they fight after Jake won't take training seriously and the ensuing fight caused multiple injuries to both of them. But, in the end of the episode, they go back to being friends again after their confrontation with the Dream Warrior.
Jake and Lady's puppies
Finn is happy to meet his nieces and nephews in "Jake the Dad" and even wore a shirt which had written upon it "BEST UNKLE" upside down. During the short period of time Finn was with the puppies, he started to play with them (such as when Jake saw him with them he said they're having some "uncle wrestling").
Finn is shown to display a liking to Jake Jr., as seen by showing a general apathy to Jake Jr.'s appearance. He also tries to cheer her up in "Another Five More Short Graybles" by joining Jake in a skit to make a time machine to help Jake Jr. in her problems of the future, even going as far as pretending to be a girl, which he did not do in "Slow Love."
In "Billy's Bucket List," it is revealed that Finn's human dad is still alive and is stuck at the Citadel (also known as the Crystal Citadel as mentioned in past episodes). At first Finn is shocked that his human dad is alive, but he is nonetheless excited to reunite with him.
Martin acts like a jerk when meeting his son and doesn't even seem to care that he has a son. When Jake tells Martin that Finn's his son he completely ignores Jake and exclaims, "Whaaaat? No starskipper?" in response to Finn telling him they didn't have a starskipper. And when Jake repeats himself, he responds by saying, "Son? Oh. Hey, good for you kid."
Martin doesn't seem to care for Finn as much as Finn cares for him. He can't even bother to remember his name, calling him "Flynn" once. When Finn asks him why he left him in the woods when he was a baby, he gave a lousy excuse like, "You know me, I'm a funny guy. It was a long time ago. Who knows, maybe you left me!" Martin only acknowledges Finn as his son when he wants something, then leaves him as soon as he gets it. Like when his leg was zapped off, he encouraged Finn to retrieve the Guardian Blood and apply it to his leg, calling him "son" and other things, then as soon as it healed, he swam away shouting, "I got to run to the store!"
In The Tower, Finn wants revenge on Martin, even going to the extent of building a tower to outer space to rip off Martin's favorite arm. After Princess Bubblegum tricks Finn, he realizes he doesn't want his dad's arm anymore, and feels "neutral."
After crash landing on earth in "Astral Plane" which continued into "The Visitor". Martin came up on a tribe of Villagers. Finn sleepwalked for two days to the village. After two days, he needed water. He drank water from the village until he heard the "tree spirit" which turned out to be Martin. Martin did not want Finn to see him. Martin was actually calling Finn his son many times throughout the episode. Finn was still bothered by him because he was mistreating the villagers. Martin, however, only acted like this towards Finn so he would help him fix the escape pod. After finding out Martin was just leaving the villagers to die, Finn became furious and sent Martin back to space. It is unknown exactly how Finn feels for him now.
BMO lives with Finn and Jake in the Tree Fort. It serves as their living video game system, film editor, camera, and many other portable electric items. It appeared in the eighth episode of Adventure Time, so it has been with them for a long time. Occasionally, Finn and Jake seem to take on parental roles when it comes to BMO, such as taking it to soccer practice or disciplining it when it misbehaves.
In "Video Makers," BMO records the footage requested by Finn and Jake, although they disagree on what genre of movie it will be, so they leave BMO a note that tells it to keep only the best footage and present it at the Movie Club. It ends up bringing them together by using both the action and comedy/romance footage and singing a song, rather than taking sides with either of them. In "Incendium," BMO's video game music inspires Finn to sing "All Gummed Up Inside," then BMO helps watch him while Jake courts Flame Princess, and pulls a kancho prank on him to try to cheer him up.
In "Be More," Finn and Jake help BMO by taking him to the place where it was born to find new core system drivers and preventing it from being wiped of its memories. It is also revealed that BMO was sent out to the world by Moe to find someone who can take care of it, and Finn and Jake were the ones sympathetic to adopt it.
Though he initially considers her an enemy in her debut, "Evicted!," Finn quickly befriends Marceline the Vampire Queen, as he learns that her seemingly evil ways are just playful teasing in "Henchman." A rowdy and adventurous character, Marceline and Finn share the same vigor and thirst for danger. One of the key reasons why they managed to forge a friendship is that Finn saved her life in "Henchman" when Jake exposed her to direct sunlight and threw garlic at her in a misguided attempt to save Finn. In the same episode Finn, in an attempt to convince Jake of her generally wholesome ways, calls Marceline "a radical dame who likes to play games."
Despite Jake's fear of Marceline (and of all vampires), Finn enjoys spending time with her so that they can be "awesome together." In "Go With Me," Finn asks her to go to "Couples-Only Movie Night," but only as a friend. Being mutually disgusted to the point of vomiting by the idea of kissing (although ironically she has kissed him on the cheek at least twice), Marceline said no to Finn when he asked her to go to the movies thinking he was asking her to be his girlfriend. In "Marceline's Closet," he accidentally sees her naked when Jake tells him to see if the coast is clear for them to get out of her house, causing him discomfort.
In "Daddy's Little Monster," Marceline jests that she does not want hang out with him anymore, but it is implying that this claim is a jest when she invites him, Jake and the Ice King in a basketball game in her house in "Simon & Marcy."
Finn became friends with Lady Rainicorn after Jake wanted to hang out with both of them at once in the episode "My Two Favorite People." At first Jake regrets introducing the two, but in the end is glad it happened. Finn and Lady Rainicorn still share a close bond, despite the fact that Finn can't understand Lady Rainicorn's fluent Korean. In the episode "All the Little People," The toy versions of Lady and Finn are seen kissing, but then Finn laughs and says "weird" which implies that Finn knows nothing will happen between them. In The Pit, Finn asked Lady Rainicorn to help him save Jake from Kee-Oth in the broken dimension.
Finn looked up to Billy as a hero and friend. In "His Hero" Finn is shown to be willing to do anything to impress Billy, but at the end of the episode, he proved to Billy that it's needed to fight sometimes, and even gained his admiration and friendship. According to Canyon, Finn reminds her of Billy when he was younger, which could explain why they became fast friends, even to the point of a slight father-son relationship. Finn still gets traumatized about his death and even remembers that time when Billy single-handedly defeated a group of monsters.
Finn had a rather obvious crush, which he denied before the events of the episode "Wizard Battle," on Princess Bubblegum, whom he occasionally calls "Peebles" and other nicknames out of affection. He interacts with her more than any of the numerous other princesses of Ooo, and would jump at the chance to do anything for her. In a sense, their relationship was like that of a prototypical royal princess/loyal knight. After his heroic duties Bubblegum would, as Finn hoped, occasionally kiss him afterward, though she hasn't kissed him (or anybody else) since "Wizard Battle."
Finn becomes very protective and jealous when someone else comes between them, as seen in "Ricardio the Heart Guy," in which he obnoxiously performing the Science Dance as a desperate ploy to attract Princess Bubblegum's attention and sought to one-up Ricardio and expose him as a villain. Later on in The Suitor, Finn expresses his jealousy through a thinly disguised veil of contempt for Braco believing him to not be good enough for her. However, when he learns that Braco is still trying to win over the princess (i.e., that he hasn't succeeded) he helps him out by allowing Braco to perform Finn's quest.
In "The Real You," Princess Bubblegum becomes concerned about Finn and his new genius identity after donning the Glasses of Nerdicon during her Science Barbecue. She assures him that she only likes Finn as his normal self. Princess Bubblegum kisses Finn on the cheek for trying to win her heart through his smarts. In "The Duke," she shows that she could never hate Finn forever after he accidentally threw a bottle that made her green and ugly, implying that she has a deep friendship with him to not be able to break it.
Finn eagerly hoped to win the princess over with his heroic deeds. Finn and Princess Bubblegum share a staunch sense of morality and often work together to bring justice and balance to the Land of Ooo. Taking several dangerous and tomboyish cues from Marceline in "Go With Me," Finn tries to set up a movie date with Princess Bubblegum ultimately, by Marceline's advice, trying to "wrestle" her and by leading wolves into her bedroom, and the Princess regretfully banishes Finn from the Candy Kingdom until he stops "acting like a psycho."
In "Mortal Folly," when Finn and Jake are chasing the Lich, the Ice King persistently nags them to give him their blessing to marry Princess Bubblegum. When the Ice King says, "It's not like you want to marry her," Finn blushes and angrily throws a rock at him. Earlier in the episode, before embarking on their pursuit of the Lich, Princess Bubblegum gives Finn a pink sweater that she knitted for him, saying that she cares about him. This sweater would later protect Finn against the Lich using the "power of liking someone a lot," as Finn put it. He later refers to the sweater as his "like-like sweater."
In "Mortal Recoil," Finn outwardly confesses to the princess that he "likes her a lot," although it is unknown whether she actually heard him, as she was still possessed by the Lich at the time. Princess Bubblegum, whose incomplete reconstruction at the end of season two (resulting from the candy surgeons' inability to completely recover all the pieces of her bubblegum body) caused her to revert to her 13-year-old self, hugs Finn after her recovery and calls him "hero."
In "Too Young," she shows much affection towards Finn. Based on her actions, this may show that this might be Princess Bubblegum's actual feelings for him if she was at that age at the time. To complete her re-aging process they share "a whopping love-hug" and a kiss. Afterward, she can only remember the hug "was, like, five years ago." Finn feels beaten afterwards, but a pep-talk from Jake brings his spirits back up. In "Wizard Battle," Finn gets a kiss from Princess Bubblegum again (her last to date) after winning the Wizard Battle. She does this to reward Finn for going to such lengths to kiss her, and for stopping Ice King from kissing her. She slaps him shortly afterwards for cheating and ruining the sanctity of the event.
As of "What Was Missing," it is revealed that Finn has kept Princess Bubblegum's wad of hair from "To Cut a Woman's Hair" and spends quite a bit of alone time with it, as stated by Jake. She becomes aware of this as Finn reveals the secret in his song.
After being rejected several times, in "Incendium," Finn becomes deeply depressed and cries over Bubblegum by a little shrine he constructed made up of two framed pictures of her, his lock of her hair, and a pool of his tears. He becomes enraged and states that he'll kill whoever started a fire that burned his two pictures of Bubblegum. After his brief encounter with the Flame Princess (who started the fire) and saying that he likes her, and later saying that he thinks he has a crush, showing that he has gotten over Princess Bubblegum.
In "In Your Footsteps," Jake says that Princess Bubblegum was his ex-girlfriend, but Finn replies "we never went steady."
In "Burning Low," Finn thinks Princess Bubblegum is jealous of his new relationship after hearing this statement from Jake; this thought is boosted by her attempts to call off the relationship, but in reality she is trying to prevent global destruction from a disastrous reaction by Flame Princess's unstable elemental matrix. When he goes to write a poem for Flame Princess, Bubblegum finds him, and tries to explain to him that "responsibility demands sacrifice." She thought that Finn understands this, but Finn angrily reacts, in which he officially reveals his feelings for her before and is ready to move on.
In "The Suitor," when Princess Bubblegum states that Braco is a suitor of hers, Finn's face drops, saying, "Oh, cool. That's cool. You're dating. That's cool." Later, Braco asks Finn for the map to the soul stone, so that he can bring Princess Bubblegum the stone, in the hopes that she will love him. Finn then tells him that "that road you're on leads to nowhere," which might be referring to his former love for her.
In "Too Old," Finn seems to have gained interest in Princess Bubblegum again due to his break-up with Flame Princess. But by the end he realizes there is more of a difference between them besides just age. He now wants to talk to Flame Princess to try to fix what he caused.
In "Rattleballs," Finn has decided to get out of his last relationship by protecting Bubblegum and following her commands. Though it was unknown if he was dedicated to Bubblegum again, he did it in an embarrassing and intrusive manner that annoys her. He also states that he served her one hundred percent like how the gumball robots were programmed. When she mentions that she's out of milk, he goes overboard and spends three weeks getting a tiny vial of special mink's milk. Later at the junkyard, he has fashioned a scrappy Bubblegum mannequin out of garbage and pretends to defend its honor, referring to it as "my lady."
In "The Pajama War" Finn and Princess Bubblegum somewhat flirt with each other. They hung out and made it work, despite their age difference.
Flame Princess is Finn's ex-girlfriend. He first meets her at the end of the episode "Incendium." During the episode, Jake poses as Finn trying to court her because he believed that Finn, depressed after being rejected again by Princess Bubblegum, needed a new love interest. However, when Flame Princess's father tells Jake that she is evil, Jake tells her (disguised as Finn) that he doesn't like her, which causes her to become confused and angry and attack him, following him back to the tree fort where the real Finn is.
She starts a fire in the house which burns the pictures in Finn's shrine to Princess Bubblegum, and he becomes enraged and runs to see who ruined his shrine. When she accidentally lights the liquid pyrotechnics left behind by Princess Bubblegum and douses her fire, he saves her and brings her into the house. When she regains consciousness, Flame Princess yells at him, "You! What's wrong with me, huh?! You don't like me?!" and Finn states, "I like you!" This statement, despite Finn never knowing Flame Princess before, however, is not evident of "love at first sight." Flame Princess blushes, then slaps Finn and warns him never to mess with her again, and flees the tree house. After she slaps him, he immediately wanted to know who she was. He then told Jake, "Dude, I think I have a crush."
In the continuation episode, "Hot to the Touch," she officially becomes Finn's new love interest. He asks Jake to help him find her, saying that he "peeped beyond her burning gaze" and that "she ain't evil," and the two run out to look for her. They spy her by a pond and hide behind the bushes to watch her. Finn affectionately likens her to "the steam off a puppy's nose searching for ham in snow" and "a cute little flower." When she curiously dips her hand in the pool and jumps back in pain, Finn rushes to her aid, surprising her. Finn admits to Flame Princess that he really likes her and they should be together, which causes her to glow brighter and makes small fires appear around her. Finn is surprised with the fire getting near him, so he tries to put them out, not knowing that by putting out the flames he would hurt Flame Princess.
Angry and confused, she runs again and the brothers chase after her, then she ambushes them. However, the attack does not last long, and Finn confuses Flame Princess by trying to compliment her while she is trying to kill them. He then tries to explain his feelings again which causes her to blush, but she resists. Upset that when Finn makes her glow brighter, he puts it out, she warns him that he "should not toy the emotions of a fire elemental." Flame Princess says that fire's purpose is to burn and proclaims that the Goblin Kingdom will be her own Fire Kingdom. Finn tries to convince her not to do it.
When they fly to the Goblin Kingdom with fire-proof suits, Flame Princess attacks them with fireballs but they have no effect. She again shoots another fireball at Finn, but this is deflected and instead hit a cart. Jake extinguishes the cart's flames, consequently hurting Flame Princess once more. Finn distresses that he doesn't want to hurt Flame Princess, but his morals say he must help the citizens of the Goblin Kingdom. Neptr, thinking he's helping, engages the foam blaster to extinguish her. However, Finn manages to stop Neptr from directly hitting Flame Princess and instead he hits Jake and a few of Flame Princess' flames, again hurting Flame Princess. Flame Princess then gets extremely angry and proclaims, "That is the last time you hurt me," and grows into her beast form. A fiery tear from Flame Princess' right eye is revealed that she is harmed both physically and emotionally. Finn shouts, "No more! No more!" and literally rips himself out of his own suit and stands on top of it, shouting out to Flame Princess. However, he is ignored.
Finn, angry and upset that he can't "just like a girl," begins to cry. A tear of his falls on the flames of Flame Princess, stinging her and catching her attention. Flame Princess watches Finn cry, confused and amazed, then stops her flames and approaches him. She says that now she believes that Finn is a Water Elemental because he "creates water," or cries. Flame Princess says that no matter how much they like each other, they can't be together because they are of conflicting elements. Finn tries to explain that he isn't, but Flame Princess has trouble understanding the concept and says even if they liked each other, they would only hurt each other. Finn replies, "No, I can take it. I mean...we can try." Flame Princess glows, touched that he "would defy nature for" her. She hugs him, and although he smiles for the first few seconds, Finn begins to burn up and pushes her away. Flame Princess then bids him goodbye.In "Burning Low," she and Finn are dating. She even thanks him for building her house and they hug each other. He decides to go to "tier two," which Jake says is "smooching" after another date, but only receives five hugs, which according to Jake, does not count as "tier two." Embarrassed, Jake then gives Finn the idea to write her a "sappy poem." When Princess Bubblegum tells Finn that he should stop seeing Flame Princess he reacts angrily, thinking that she is jealous. Jake is also angry at Princess Bubblegum, as he believes that she is trying to sabotage Finn and Flame Princess' relationship, when he just wants Finn to be happy. Princess Bubblegum explains that extreme romance, such as kissing, will cause Flame Princess's elemental matrix to become unstable and burn the planet from the inside out. He and Princess Bubblegum then try to stop the kiss, but arrive to see them already kissing. When Flame Princess falls into the earth's crust due to her instability, Finn goes in to save her. Princess Bubblegum tells Jake to cover the hole and cut off Flame Princess' oxygen supply, so that she cannot burn. After using artificial respiration to revive her, they continue to date. This whole episode proves that, whatever challenges be thrown at Finn, he still will continue to love Flame Princess.
In "Ignition Point," Finn and Jake go to the Fire Kingdom to retrieve Flame Princess' scented candles. He refers Flame Princess as his "lady." Flame King tells Finn that his daughter is evil. However, when Finn asks him if she could become good by hanging out with someone who is also good, Flame King replies yes, which gives Finn the motivation to change her to good.
In "Reign of Gunters," Finn takes the advice of a dating book called Mind Games and tries to act more mysterious, claiming he needs to keep all the ladies in a state of confusion; that way, he has "options in case Flame Princess doesn't work out." This attitude might be because of the influence the book has inflicted upon it.
In "Vault of Bones," Finn knows Flame Princess is good by his heart, so he goes to a dungeon with Flame Princess to prove to her she is good. Together, they traverse the dungeon, with Finn teaching her how to properly dungeon crawl. She thinks his methods are boring, and, due to her destructive personality she opts to just burn through everything with her elemental powers. However, when Finn is trapped by a Giant Goo Skull, Finn warns Flame Princess not to use fire to defeat it. She instead defeats it the way Finn taught her to—by intimidating it. She assures Finn that she'd never hurt "[her] boyfriend," and afterwards, she says that she had a great time.
In "Puhoy," Finn says that he told Flame Princess a joke, but she didn't laugh, which causes Finn to worry about the status of their relationship. Upon returning from the Pillow World, Flame Princess calls him, saying that she finally got his joke, and she thought that it was funny.
In "Jake Suit," it is shown that Flame Princess wants to introduce Finn to her less evil family members, but due to Jake's manipulation of Finn due to a bet, he ultimately wrecks the gathering. Flame Princess goes outside and confronts Finn about the situation, but then discovers that Jake is manipulating Finn to induct pain from him. Even though Flame Princess admires how Jake tries to cause Finn pain, she ultimately wishes Finn good luck at the bet.
In "Frost & Fire," after Flame Princess beats up Ice King, Finn begins to have dreams with the Cosmic Owl in it, but keeps waking up before the dream ends. In order see the dream ending, he continues to pit Flame Princess and Ice King against one another by writing insulting messages about them and claiming the other sent it. They have a final battle in the Ice Kingdom, which eventually melts because of Flame Princess. Finn passes out from the heat and the dream ends with the Cosmic Owl saying he "blew it." After Finn awakens to Flame Princess on a rampage, he goes and saves the defeated Ice King and admits to sending the letters. This betrayal and the hurtful things in the letter that only Finn would know about causes Flame Princess to walk off saying she needs some time by herself. Ice King repeats to Finn that he, indeed, blew it.
In "Too Old," Finn moves on with the breakup with Flame Princess but was short-lived as he failed to restore his past relationship with Princess Bubblegum and realizes that there is just too much differences between them to ever have a real relationship. He then realizes how much he messed up with Flame Princess and decides to talk to her soon and fix what he has done, but gets nervous when Jake jokes that she might have gotten a new boyfriend by now.
In "Earth & Water," when Finn apologizes to Flame Princess, she accepts it. In response, Finn asks if they are still going out. Flame Princess says no but that they can be friends. She tells him he can visit her any time in the Fire Kingdom as long as he is completely honest with her, and he looks upset - but nods in agreement.
In "The Pit," he states that he still loves her.
In "Red Throne," Flame Princess asks Finn to help her reclaim the Fire Kingdom after a coup by the Flame Lord and Flame King. However, Flame Princess states that she no longer has any feelings for Finn. Finn tries to impress her with his grass sword, improved swordsmanship, and barging confidently into the Fire Kingdom, all of which fail to reclaim her kingdom and get them both caught and imprisoned. Cinnamon Bun saves both Flame Princess and Finn. Cinnamon Bun then admits his love for Flame Princess. Finn mutters "Geez, did I just get shown up by Cinnamon Bun?"
It is stated in "Breezy" that Finn no longer talks to Flame Princess, which implies that he believes she and Cinnamon Bun are dating. Which was confirmed not to be true by the writers and Cartoon Network's Official Twitter Page.
However, in "The Mountain", while Finn is looking through his telescope, he spots Flame Princess rehearsing a dance with Cinnamon Bun. His reaction is that of slight longing, and perhaps contempt, igniting his decision to follow Lemongrab up the mountain, in order to distract himself from seeing his ex-girlfriend. Flame Princess also appears in the mirror as one of the three choices along with a butterfly and Princess Bubblegum, indicating that Finn might still have feelings for her, or isn't over her just yet.
RoselinenIn "Puhoy," Finn meets Roselinen, his third love interest, in the possibly-imaginary realm of the Pillow World. Finn enters this realm to let his mind unwind, as he is having supposed relationship problems with Flame Princess; when he meets Roselinen, she asks him to dance, to which Finn replies "I have a girlfriend." She insists that the gesture is purely platonic, and they dance. As they talk, she shows signs of liking him, and Finn talks half-embarrassedly.
Eventually, as by this time, Finn believes there is no way to escape the Pillow World, Finn abandons his relationship with Flame Princess to start a new life with Roselinen, having two kids named Jay and Bonnie. When Finn finds out there is a way to escape the world, he is fully willing to go, though torn up about leaving Roselinen and his family behind. Roselinen asks Finn to not forget about them. Finn grows old and returns to his world at the point of his death in the Pillow World. When Finn returns to his world, he is about to tell Jake about his "dream," when Flame Princess calls to say she gets his joke. After Finn tells Jake about his phone call, Finn forgets all about the dream, and also forgetting Roselinen and his family in the process.
In the episode "Breezy", a to-be-queen bee, Breezy, is attracted to the flower where Finn's arm used to be. As time progresses, she discovers that she not only likes Finn's flower, but has a crush on Finn himself. When Finn is threatened by the other bees, Breezy drinks the "royal jelly" to transform into the rightful queen bee of the hive and save him with her new-found powers. She confesses her love for him, but Finn declines the offer to be with her, stating that the feeling is simply not mutual.
Erin is Finn's non-canon love interest whom he meets in "Food Chain." Finn immediately falls in love with her beauty the moment he saw her. After a short interaction with each other, they jump to a quick conclusion to get married. At their marriage, Finn was nervous at first with Erin's beauty and as they were about to kiss, a pair of birds suddenly came and attacked the caterpillars. Finn and Erin tried to escape, but went flying then falling. Before Finn went back to normal, he vowed to Erin that he'll marry her again when they meet again in a different lifetime. When Finn turns back to normal, it is unknown what happened to her.
The Lich's desire to kill off life brings him into constant conflict with Finn. They first meet in "Mortal Folly," although it is implied in "His Hero" that Finn already knew about the Lich, where the Lich is freed from his prison, goes on a rampage and tries to regain his power to destroy all life. In the episode, the Lich tries to dip Finn in his Well of Power, implying that the Lich believes Finn should be on his side. He also states that he believes Finn is his inferior.
The Lich was shown trying and succeeding in manipulating Finn's emotions to his own gain several times. This was first shown in "Mortal Recoil," where the Lich (disguised as Princess Bubblegum) manipulates Finn's romantic emotions toward Princess Bubblegum and makes him hand over the things he needed to regain his powers and continue his quest to destroy all life in the Multiverse. Later, in "The Lich," the Lich (disguised as Billy) uses Finn's trust of Billy and makes Finn get the gems of power, which he connects with the Enchiridion and uses to travel to the center of the multiverse and the wishmaster Prismo.
As a recurring antagonist, Ice King is frequently at odds with Finn. Finn is prone to impatience and aggression around him but also shows him sympathy, as in "When Wedding Bells Thaw." However, Finn's aggression never outweighs his compassion, honor, and respect for life, as evidenced when he refused the opportunity to slay Ice King as Billy had slain the Fire Count. Similarly in "Mortal Recoil," Finn, albeit grudgingly, trusted and united with Ice King against their common enemy of the Lich-possessed Princess Bubblegum. The Ice King competes with Finn for Princess Bubblegum, which is one of the sources of antagonism between them. This mutual attraction for Princess Bubblegum can be clearly seen in "Mortal Folly," where Ice King continually pesters Finn for consent to wed Princess Bubblegum. Upon Ice King's saying, "It's not like you wanna marry her," Finn blushes and hurls a rock at Ice King.
Finn and Jake sometimes appear to spy n the Ice King the Ice King like in "I Remember You," and "Chamber Of Frozen Blades," which in both situations, they were spying on the Ice Kingdom, and more extremely so in "Chamber Of Frozen Blades," where they actually go into the Ice Palace and search for signs of captured princesses.
Although Finn and the Ice King began as bitter rivals, their relationship progressed in the later episodes to a friendly rivalry, then an odd friendship in its own right, and finally a genuine friendship.
The Ice King does not really hate Finn and Jake, as he only fights with them because they are morally opposed to each other. He frequently tries to be friends with them, in his own, misguided ways, and has willingly made alliances with them. In the episode "Still," the Ice King freezes Finn and Jake so they can have "bonding time." It was shown in "Hitman" that while Finn and the Ice King are rivals, they are not enemies, and don't harbor any real malice towards each other. The Ice King made it clear that he doesn't want to kill Finn, the most he would do is punch him in the belly and make him vomit up his lunch. At worst, they are battling rivals, as Finn openly disapproves of the Ice King's habit of stealing princesses and causing mischief. At best, they are playful rivals, even friends.In "Holly Jolly Secrets Part II," the Ice King has a locket with the pictures of Finn and Jake. Near the end of the episode, the two are shown snuggled up side-by-side by a roaring fire, wearing ugly Christmas sweaters. Finn's attitude towards the Ice King has softened since discovering the tragic secret of his origin, and his compassion for people in distress outweighed his petty squalls with him enough to be his friend.
In "Mystery Dungeon", Finn is shown to kind of finally understand how sad Ice King is.
In "Beyond this Earthly Realm," Ice King tricks Finn into putting all the creatures of the spirit realm into the spirit hole, saying Finn would be freed from the spirit realm if he did so. However, when Ice King accidentally falls on the porcelain lamb, Finn and Ice King help each other to be freed from the spirit realm by affecting the material plain and breaking the porcelain lamb.