Martin is not powerful. He is a charming liar. In "The Visitor" (Ep 26), he lands on a distant planet, gets a woman pregnant, and abandons the child to a monster. He justifies it all with a shrug. The show forces Finn (and the audience) to accept that sometimes, parents are just broken people who make terrible choices. There is no redemption arc. There is only acceptance.
Mid-season introduces the show’s best cosmic bureaucracy. In , Martin returns, only to crash a ship and reveal he has no memory of Finn’s mother. "Is That You?" (Ep. 19) is a masterpiece of time-loop storytelling, focusing on Jake and Prismo’s relationship, rewriting the rules of multiverses in Ooo. Adventure Time Season 6 Complete -Episodes 1-43-