BMO

BMO (phonetically spelled Beemo) is Finn and Jake's living video game console, portable electrical outlet, music player, roommate, camera, alarm clock, toaster, flashlight, strobe light, skateboarder, friend, soccer player, video editor, and video player. It makes its appearance in the title scene of the theme song of every episode of Adventure time, just as Finn and Jake pound their fists together. BMO is characterized as a loyal, trusting, and helpful friend who is protective of Finn and Jake.

jake

Jake (full title: Jake the Dog) of Adventure time, is a
magical dog and Finn's constant companion, best friend, and adoptive brother. Jake has stretchy poewrs  (which he has had since he was a puppy), which allow him to stretch and manipulate his body, coming in handy on innumerable occasions throughout his and Finn's adventures. He is the son of Joshua and Margret. Jake has a brother named Jermaine. Jake is 28 in magical dog years, though he rarely acts mature. Then again, h

ow exactly magical dog years correlate to human years remains to be seen.

Finn

AdventuretimeFinn

 As shown in ," Finn appears to have been abandoned in the woods during infancy. He reveals that he made "boom boom" (Finn's word for defecation) on a large leaf, fell on it, and lay there crying until Joshua and Margret (Jack's parents) rescued him from the wilderness to raise him alongside Jake, who becomes like a brother to him (as such, Jermaine is also Finn's adoptive brother). In "memory of memory," a baby Finn is seen singing a song in the bathroom of what appears to be Joshua and Margret's house. In "henchmen," when Finn is asked about his parents, he says Jake told him that he came from a cabbage, in jest. In "Susan strong," Finn states that he knows nothing of his human parents or any other humans.