In ' The Visitor,' he is seen to be living with a large group of small villagers and manipulating them to believe in a tree spirit in order to help him build his escape pod. Grob Gob Glob Grod mistook his ship for the Catalyst Comet and sacrificed himself by flying at the comet and sending it on a course for Earth instead of Mars.
In ' Astral Plane,' it is revealed Martin found a spaceship after the events of ' Escape from the Citadel' and was going to crash on Mars. He ultimately causes Finn's arm to be removed, as he tries to escape the Citadel while Finn is holding on to the escaping portal, causing Finn's grass sword to take over and remove itself and part of Finn's arm. He runs away from the problems at the Citadel as the Lich spreads his evil. In ' Escape from the Citadel,' he is finally revealed but has no clear memory of his son, Finn, or why he deserted him. The episode cuts to a brief scene that shows a silhouette of a man trapped in a crystal aboard a massive space station. Billy explains to Finn that his human father is trapped in the Crystal Citadel. He was first revealed in ' Billy's Bucket List', albeit briefly.
