One of my players is playing an Alchemist which he's very much enjoying, and he has expressed worry that when his character dies he'd have to make a new one and that he'd rather continue with what he has been building up.

What I'm thinking for him is that in the case where his character dies, his body gets taken to a type of laboratory where through experiments he's resurrected, since he accidentally signed a contract where he sold his body to science (which he was unaware of). The thing is, I want there to be a 'catch' to this that does to some degree make his death have a lasting impact.

This could be stuff varying from 'he now has a third ear' to 'he is now cursed/zombielike'.

Any ideas for balanced yet interesting changes to a character who was just (accidentally?) resurrected by scientific experiments?