The truth in “Bad Blood” winds up being somewhere in between Mulder’s conviction that vampires are up to no good, and Scully’s early theory that the killer is someone who wishes they were a vampire.
The killer is Ronnie Strickland–played by Patrick Renna of The Sandlot fame–a pizza delivery guy who laces his pizzas with drugs before killing them,.
Ronnie is, in fact, a vampire, but not the kind of vampire we’re used to. He doesn’t have fangs (beyond the plastic ones), the Sun doesn’t burn his skin, and considering what he does for a living it’s a safe bet garlic isn’t an issue.
But he wants to be the type of vampire we’re used to. He’s a vampire who wants to be a way cooler vampire.