Malasha settles on a heavy stool.  "It's in the nature of things, that sooner or later, vampire childer leave their Sires.  But every so often, one like Angelus will decide he wants a permanent childe.  One sweet, devoted, submissive, and dependent on them, but strong enough to kill anyone else who dares to touch them.  He finds a likely candidate, like the lovely young man William was, and turns him.  Then he makes sure that childe feeds almost exclusively from his body.  For ten or fifteen years, at least.  On top of the physical and psychological conditioning.  At the end of that time you have a perfect mate for life, from a Master Vampire's point of view.  And if Angelus hadn't gotten a soul, that's how it would have been.  But he did.  And he abandoned the mate he's spent two decades molding to his will."