|The following information is from the Adventure Time comic book series.|
It may not be part of the same canon or continuity as the animated series.
Issue 9 of the Adventure Time comics.
Finn and Jake go slightly too far back in time, arriving at the time of Issue 1. They travel again and end up at the original pilot episode. Finn remarks that this is back when he made everyone call him Pen because he loved pens so much, and admires his past self dancing. Jake takes Finn's sleeping bag from the past and they return to the time machine. Finn tells Jake to return the sleeping bag or he will mess up history, but Jake reminds him that this is when he lost his sleeping bag, so he is supposed to take it. This makes Finn realize that he was the one who left a note for himself in the past explaining that he should use his real name and that he borrowed his sleeping bag. He leaves the note and Finn decides to drive the time machine because it only has one use left and Jake has gone to the wrong time twice.
They arrive in Issue 5 and explain to BMO that they are from the future. They let BMO know that they appreciate the robots he made, but they become evil when they get wet. BMO understands and the three destroy the robots. BMO points out that now that Finn and Jake have older bodies, they will be "wimpy old men way way sooner".
Finn and Jake go to Princess Bubblegum for help. Finn suggests that Princess Bubblegum pour science on their time machine to make it work again. She agrees, and just before they use it, Jake reveals to Princess Bubblegum that she and Finn kissed in the future, much to Finn's embarrassment.
Finn and Jake re-appear in their normal bodies and talk to Princess Bubblegum, who is confused because the time machine she just finished disappeared. Finn mentions that the time machine they used disappeared too. Princess Bubblegum is even more confused, but is interrupted by her alarm to remind her to go to the Royal Court. Finn and Jake decide to keep their time travel a secret because they are the only ones who remember. Finn deposits one ruby in the bank to pick up in 15 years just in case.
They return home and realize that because they went back in time again, the robots haven't been destroyed. Jake destroys them again while Finn explains why to BMO again. The scene cuts to Finn, Jake, BMO, and Princess Bubblegum (after returning from the Royal Court) playing video games, concluding the time travel story arc.
Comic preview pages and panels
- This issue provides a reason for Finn being called "Pen" in the Pilot episode. He loved pens so much that he forced everyone to call him Pen. The comic series is not necessarily canon with the main series, so this may not be canon.