Desmond hung his head a little as he heard her ask the question that he most certainly did not want to answer for her. He knew that it was coming before she had even started to speak again, but there had been that moment of vain hope that had told him that maybe she would not be curious like so many others were, that she might just let that question slip by. A part of him wanted to vanish at the idea that she was going to ask him the question about why it was that vampires drank only sometimes from humans. It reminded him of Magdelena, and of Beth, and of things that could not be changed, boundaries that could just simply never really be crossed. And that realization made his heart hurt far worse than any hatred of him that she might have had from the fact that he was a dhampir.
"It requires a bond." Desmond said simply, intentionally being vague on the matter. He could hear the way that she spoke about him taking blood and he knew that it was not in a way that remotely understood what feeding was like. There was a reason that vampires did it, and not only did it but reveled in the fact that they did it. It was like a drug, an intoxicating wonderful drug. Like satisfying your deepest craving and fulfilling all of the lust inside of you after being celibate for a century and being wrapped in sublime happiness all rolled into one. It was something that was shared both by the feeder and the one being fed from, unless for some reason the creature doing the feeding had some sort of twisted obsession. Much like human sex, feeding for vampires was based off of their personality, and Desmond had met more than a few vampires that delighted in terrorizing their victims as they fed, denying them any pleasure in it.
"It is a life bond. It cannot be broken until death." Desmond said simply. It was not exactly a secret amongst dhampir. Vampires had been the first to learn about it, and the most aggressive to exploit it. Though Desmond was certain that there were others who had tried over the years. Vampires were always the most prevalent, however. It stemmed from the fact that few other creatures really wanted to see a dhampir be changed to a vampire and shed their humanity completely. Indeed, Desmond had known dhampir who had taken that road. It certainly was the easiest road to take. Not that it was without it's own pitfalls. Even though they were accepted, a half breed was always a half breed. Vampires when learning of a dhampir that had converted would often look down upon the dhampir and treat them as if they were a second class vampire.
Still, there was nothing that delighed some vampires more than the idea of watching a dhampir 'lower' themselves to drinking blood the same way that they did, living as they did, afraid of the sunlight. It was a frightening revelation that much like a human, a dhampir could be 'forced' to convert over to being a vampire. The thought of it, while once tempting, had long since lost its appeal to Desmond, and now really only served to turn his stomach. But even as it turned his stomach, he could still feel that part of him that gnawed at him. It was another thing that vampires loved to use against dhampirs, and something that was widely known amongst their kind. Once a dhampir had been given a taste, they would always feel some pull towards it. It could be managed, of course, with time. But it would never go back to the same way that they had been before. They could never return to that blissful state of ignorance before they had ever sampled human blood, before they knew what it tasted like for certain.