Re: Not to beat a deceased equine into the ground . . . From the way everything in the canon reads, it was actually Lucrecia who "caught" Chaos, using research she had done with Vincent's father.
Oops! I have the cut movies from DoC, so I have no excuse for that failure of memory. Right, it was Lucretia who trapped Chaos inside Vincent.
And yes, gods bless our mad scientists who provide us with our emo-soaked lust objects. :-)