none of which are mutually exclusive

What kind of fetishes does the ice king have

Foot fetishes. Cause of his wife ring and extramarital relationship in 5 more short graybles

Finn's?

finn's fetishes are (evidently) pillows, fire, candy and maybe vampires

also butt stuff

but really, I'm pretty sure finn is into pretty vanilla stuff, but maybe when he's feeling risque, he's into fem-dom because he's interested in role reversal as the hero.

Because of flame princess I think he might have a little masochism with fire going on there