Yes, the one victim we've had was a vampire, but that vampire HAD A NIGHT KILL ABILITY.

That doesn't imply that vampires are saints- all it implies is that there are vampires with Night Kills, and some other person/persons/Hippos with Night Kills.

So, yeah. We know for a fact that a Kill-capable vampire existed. It seems pretty reasonable to assume that Stephen's Night Kill stemmed from the fact that he was a vampire. Meaning, it is likely that Yuna ALSO has a Night Kill. That right there is grounds enough for me. But, there's more!

-As I said, I woke up feeling "drained." The most reasonable theory I have is that a vampire managed to get a few nibbles of me. (In RPS mechanics terms, maybe that means it was an RPS tie, or maybe my attacker has to win on two nights to kill?)

-Finally, the "ALLEGED" anti-undead soap. I see no reason to doubt that it works, and you trying to undermine its credibility on the basis of, well, nothing, is troubling, to say the least.

Occam's Razor. Sure, maybe one vampire had a Night Kill while another didn't. And that I was hit with some non-canon "draining ray" instead of being bitten. And that the peddler is selling fake protective soap. But it's much simpler if my theory, that Yuna (or another vampire, I suppose) attacked me last night, is correct.

• Note: This is why I wanted to know if you had targeted me last night. Since you are declining to comment, I'm working on the assumption that you did not.

• Note 2: An anti-undead role would be cool, but if that were the case I hardly think I'd be so blatant about it. Plus, there isn't really any kind of "vampire hunter" group or character in Discworld canon that I can think of. Nearest is Commander Vimes' well-known prejudice against vampires, and even that is more out of habit than maliciousness.