Ice king was the main Evil-Doer in Adventure Time. But who's to say he can't

change his ways? He helped Finn & Jake Save Princess Bubblegum when The Lich possesed her.

He also has helped them out several times in past.

For instance, Finn was having trouble with Flame Princess  and Ice King Was totally innocent when he got beat up. And that time when he just  simply wanted to be happy.

Yes ice king has messed up in the past, but ask yourself,  is this poor old wizard forgivable?

As simon Petrikov once said It's not me it's the crown, please forgive me for whatever i do"

Ice king rocks

The Ice King Losing Another Battle