Marvel Sergie is a serval, margay hybrid and a member of the Graves Gang. He has yellow beige and cream fur, yellow scleras, and dark green irises.

Marvel Sergie was born in Mexico and immigrated to the Americas with his parents and three brothers. Marvel's parents started their own Mexican bakery called La Panaderia, where Marvel usually worked as a clerk and loved baking with his family. A large storm hits the bakery, destroying it. Now low on money, Marvel's parents force him and his brothers to leave their home when he's 13. Marvel lived on the streets for a while before taking interest in an abandoned warehouse in Oregon. He meets Jenni Graves and helps her rescue Myles Howler's family.

Marvel is a happy-go-lucky, optimistic cat whose goal is to be a therapy cat in the future. He is easily trusting and naive, but he never fails to see the best in everyone and everything. He views his life as a game, and willingly tells his tragic story as if it were a funny anecdote or at least tries to. He is endlessly loyal and persistent in his desire for friendship, even in the face of others' hostility. He has proven to be sympathetic when he comforts Jenni through a panic attack. He is appreciative and grateful for the little that he has, expressing disinterest in killing or even insulting people purposefully even when Mordecai suggested that he came from hilbillies due to his love for friendship.

Trivia:

Marvel's name is a mix between serval and margay, his species mixes.

He is the only hybrid feline on the Graves Gang.