Filtered from villains
I know, nothing good ever came from those words, on any world. But I think this might be of interest to you.
I was at a bar: I'd determined that this was a hanging out spot for elder vampires, and they were not of the "dracu-vamp" variety (I've been watching them for some time). I've some knowledge about this world, to the point where I can match them in a fight. There were other patrons, but they were either younger vampires or persons of an unsavory nature. Once I revealed myself, we engaged in battle and I wounded a few of them, killing some, though they put up a fight respectably. But here is where things took an interesting twist.
There was a man there. I thought he was human at first, but he got up from the table he was sitting at, approached the area where we were fighting, and then slashed his wrist with some kind of piercing weapon, before we knew what he was doing. It was some kind of greenish fluid which flowed out of the wound, and the effect could not have been more instantaneous. I had to teleport to safety before whatever I sensed affected me as well.
Every vampire in the room was in pain. They didn't die, but the blood that was in them was regurgitated. It was like their bodies were rejecting it. They were weakened severely, and it allowed him to have his pick of who he went after. The humans he came within close proximity to collapsed as well.
I quickly got out of there, because other people soon started arriving. The man dragged one of the vampires off with him. I don't know where he went. I suppose I should have stopped him, if only to determine what he was, but I was more concerned with my own safety. Whatever this man is, he appears to be some kind of walking biological weapon. As for his description, he was a tall man with brown hair and a medium-build, wearing a long gray coat over a formal suit. I've seen him on the board here, I'm almost positive.
If you come into contact with this man, do not under any circumstances pierce his skin. It reminds me of a spell we have back home, the "Font of Putrescence", which turns living flesh into a toxic pool of fluid. Except here, the toxic substance is already flowing underneath this man's flesh.
[ooc: Based on what I've seen in X-Files lore, I'm going with the theory that the virus wouldn't affect the vampires themselves, but would coagulate the blood inside them, causing an adverse effect. The bounty hunter then has free reign for a few minutes. ;)]