Nathan shrugs. "Vampires have no choice but to not-sleep all the time, humans have no choice but to do some sleeping but can do it whenever, that's how those traits happen to combine. Half-vamps are about halfway between humans and vampires in most ways, including speed and strength. They can drink blood or eat food, either one, they mostly like blood or the synthetics of it better though. They don't get sick. They heal about like vampires do, but they're more - biological, with heartbeats and needing to breathe and everything."