Lemongrab 2's actions and behavior in "Too Old".
To refresh your memory, Lemongrab 2 was created by Princess Bubblegum because the Earl of Lemongrab was obviously in need of a friend (Spying on candy people). With Lemongrab 2 being made, the two became friends and let everyone that Lemongrab had captured (Including the Princess herself and Finn) out of the dungeon.
They presumably had a fair and loving brotherhood until "Another More Five Short Graybles" where Lemongrab apparently ate Lemongrab 2 alive because he smashed a china doll. This shocked alot of viewers and changed the way he was looked at.
Lemongrab wasn't shown being eaten, but being crammed into Lemongrab's mouth and screaming in terror, "THE END! MY END!" and was just thought of being dead.
Yet Lemongrab 2 made his last (and most likely final) appearance in "Too Old". He has no legs, requires a machine to move, and the better side of the left part of his head is gone. Lemongrab is incredibly obese in this episode. It's evident they hate each other. After the Earl welcomes the Princess, LG2 tries to welcome and is screamed at. At dinner, Lemongrab shows examples of being fat, like eating a Lemon Child's bread, their only food. Lemongrab 2 is kind and not a tyrant, and gives the Lemon Child half of his bread. Several moments later, Lemongrab screams "UNACCEPTABLE!" in regards to the poor entertainment, and Lemongrab 2 mutters, "Acceptable." The Earl keeps screaming while Lemongrab 2 keeps muttering. When Princess Bubblegum and Finn are imprisoned, Lemongrab 2 lets them out. Lemongrab becomes enfuriated and jumps on the skinny figure of Lemongrab 2. Finn is the last one out the door, and sees Lemongrabs arm, which was trying to push off Lemongrab, get dragged away by a slurping sound, meaning that Lemongrab was killed and his arm let go because he was no longer alive.
I do not want to spoil what happened, but Lemongrab orders the Lemon Children to attack, and as Princess Bubblegum, Lemonjon, and Finn are about to be killed, slight screaming is heard, and Lemongrab 2 breaks out of Lemongrab's mouth. LG2 proceeds to take out a control panel and releases the metal cuffs off the Lemon Children's necks, and Lemongrab, slowly being crammed back into Lemongrab's mouth, keeps yelling for them to not follow Lemongrab. Because of LG2, Lemongrab is much less of a tyrant.
Lemongrab sacrificed himself, and I hope he is at least mentioned by Finn or someone else before he's forgotten/