Re: Tetsuya Nomura Collaboration: Utada Hikaru's Cover Album
Actually, that happens if you mess with their hearts, I think. You have to make their hearts collapse in some way to create a heartless and a nobody.
If you make them bleed to death or do a mortal injury to the body, THEN someone can actually die. We haven't seen more than 1 whole person get truely killed in the games so far (Master Eraqus), and yes his heart survived(yes that's from spoilers I read, I didn't think until recently I'd ever get a chance to play Birth By Sleep). I think if Xenohort's going to get killed though, no one is going to harbor THAT heart. It'll be a Voldemort situation (I think you've read the final book of that, right?) tho if rebirth is also part of the story, it might not be permanent, but he won't have his memories anymore when he comes back as a baby...