|Introduced in||"Crystals Have Power"|
|Latest appearance||"The Pit" (mentioned)|
|Voiced by||John DiMaggio|
Jermaine is Jake's brother, adoptive brother of Finn, and son of Joshua and Margaret. He is introduced in "Crystals Have Power" in one of Jake's flashbacks where they were both children. Jake hurt Jermaine in the flashback, which seems to have left an impact on Jake causing him to avoid violence as a way of solving problems.
After Jake hits his head and apparently begins a spiritual communication later in the episode, Jermaine tells him that he understands Jake did not mean to hurt him. Jermaine explains that they are able to talk in this manner because they are both dreaming at the same time (though Jake does not appear to be dreaming or otherwise affected by hitting his head).
A photo of Jermaine, alongside Joshua and Jake, is seen in Finn's memory in "Memory of a Memory." In "Jake the Dad," a hologram of his younger self is seen in Mom's manual with Finn and Jake. Although Jermaine's age is unknown, he seems to be around the same age as Jake, considering they were both babies in Margaret's manual. Joshua briefly mentions Jermaine in a videotape in "The Pit" when telling his children where he has gone searching for Kee-Oth the Blood Demon.
Jermaine resembles Jake, but with missing teeth, slight chin stubble, and prominent eyebrows. In Jake's flashback, Jermaine was wearing boxing gloves. He also appears to be slightly flabbier than Jake.
No, man, we're just dreamin' at the same time.
Yo, that was an accident, I knew you were just horsin' off!
- According to Kent Osborne, "Jermaine's off doing his thing and he likes to paint, but he doesn't really like to travel."
- Jesse Moynihan mentions on the Season 2 DVD Commentary for "Crystals Have Power" that he has tried to find a way to use Jermaine in several episodes, but has not been successful yet.