there are alot of dark and disturbing things in cartoon, people just don't think of it much nor the full meaning of those parts....but you're right its one of the darkest yet most awesome in my opinion
I was just imagining how he killed him(self?). They never actually showed it considering it was a kid's show. At first (and for reason), I thought he ate him but now that I think about it, he most likely strangled him to death because he's cruel like that.
I personally have him either keep him alive as a slave hidden from the rest of the world and he just wounded him before taking off with his body, or he ripped out his heart 'cause he was calling Danny a heartless SOB for letting Vlad do that to them.