He was in a prison in space. He could have known about that years ago.

Right…

How did he even traveled to space? Explain to me that.

But that doesn't explain why he was in that prison to begin with.

Exactly!

Or maybe he doesn't. At ALL.

Huh huh.

He's right. Death's job is to send the souls of the dead to the dead world to maintain the balance between life and death. The Lich, however, is trying to destroy that balance by purging the universe of life.

Or maybe we will. Just not yet.

No more cosmic parties.

Slade… :(

You know, I have the theory that Finn's dad may be suffering from the same problem that Simon (a.k.a Ice king) has. They have no memory of their past. The only difference is that Simon lost his memories due to a magical crown that deteorated his mind with time. How Martin lost his memories is still a mystery.

Or maybe he just lost his memory and can only remember his name and nothing else.

Although, he didn't look that evil, And why would he be in that prison anyway? There must be a reason behind that.

In the unused storyboard for the episode "Finn the human" it is said that he was wrongfully arrested and sent to the crystal citadel. Maybe something like that happened to him.

I doubt it.

Apparently.

And the same could be said for Finn's father as well.

Yeah. I guess.

Maybe. But maybe he's a punk that doesn't remembers who he really is.