The following information is from the Adventure Timecomic book series. It may not be part of the same canon or continuity as the animated series.
Adventure Time Vol. 4: Bitter Sweets is the forth graphic novel in the Adventure Time series. It is written by Kate Leth and drawn by Zack Sterling.
It’s that lovely time of year where Princess Bubblegum gets to leave the Candy Kingdom and venture out into the outer limits of Ooo. But when her annual quest to visit old friends takes a dark and unexpected turn, it’s up to PB and Peppermint Butler to keep the peace by using the true power of friendship. Written by New York Times bestselling author Kate Leth (ADVENTURE TIME: SEEING RED), and illustrated by New York Times bestselling artist Zachary Sterling (ADVENTURE TIME), BITTER SWEETS is a deliciously twisted adventure with a surprising aftertaste.