What are dhampirs/dhampires?
Dhampirs are a part of Eastern European vampire lore — Romanian, if I remember right, although some gypsy vampire belief systems have the same kind of thing. In those cultures, vampires are believed to be invisible, but can be seen by a dhampir (or dhampire, depending on who you ask). Dhampirs have this ability because they are the children (always sons, in the legends) of vampires and mortals (in the legends, always of a male vampire and a mortal woman). Depending on the legend, dhampirs may be able to see vampires automatically, or they may have to enact some sort of little ritual, such as putting their clothes on backwards, looking through a sleeve, etc. The typical dhampir story has a vampire bothering a town. A wandering dhampir comes through, hears of the town’s troubles, and offers to kill the vampire, for a fee. The dhampir would go out into the town square and call out a challenge to the vampire, asking him to meet the dhampir in the town square the next day. (Vampires in the