[Damon stares at Rex expectantly. This is the simplest way to do it, and Damon has done it more times than he can remember. He does look vaguely amused by Rex's comment about needing water when it is over. Fortunately, they do have some water on hand for human guests.]

[He watched Rex drink. As the other does so, he takes in more than nanites. The blood of a vampire from Damon's world is a powerful healing agent for humans. It can allow a human to heal from an otherwise fatal injury. Damon is hoping that the two things combined might be enough to help Rex.]

[Before it can do so, however, Rex is falling to his knees and looking sick to his stomach. Damon shakes his head, watching as the skin of his wrist finishes knitting back together in a few seconds. He then moves unnaturally fast and returns with a bottle of water, holding it out to Rex.]

Here.