Jermaine the Dog

Jermaine is the brother of Jake, adoptive brother of Finn, and son of Joshua and Margret. 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 didn't mean to hurt him. Jermaine explains that they are able to talk in this manner because they're both dreaming at the same time (though Jake doesn't 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."

Appearance
Jermaine resembles Jake, but with missing teeth, slight chin stubble, and a partial unibrow. In Jake's flashback, Jermaine was wearing boxing gloves. He also appears to be slightly flabbier than Jake.