Wonder how a vampire legionnaire would work out? It's not exactly a benign or positive power, unless he/she could also manipulate blood to slow people down, make them collapse, etc. Some of Anne Rice's vampires were "okay guys" but they still wanted your blood. Terry Pratchett also had a vampire family, and the mother had sworn off drinking - human blood, that is. She even went to something like an AA meeting.
If we had a vampire legionnaire, I like the idea of Lydda Jath as the candidate! She could date Ra's al Ghul, the blood guy!