Help me frame an NPC

[Dragonlordmax]

I'm running a Buffy game over at RPG.net. In the next episode, I want to introduce a new NPC - a Watcher apprentice coming from England with information for the PCs and also to study with the Slayer and her Watcher. Long term, I want to use her to create drama, with her not necessarily getting along the PCs. But that'll happen over time.

In her introduction, however, I want to set things up such that she may appear to be a demon which has killed the real Watcher, in the hopes of setting up an interesting episode and getting things off on the wrong foot. Specifically, I kind of want her to be hunting a monster (I'm thinking an impersonation monster, going after the Slayer, perhaps) in a way that gives the impression that she's evil. This is not that hard; I can make set her up without too much trouble. My problem is, if she's hunting this monster, if she tells the Watcher and Slayer about it, and is very up-front and helpful about things, it's hard to make her a suspect. If she doesn't, then she looks extremely irresponsible, to the point that she'd probably be fired. If she's affected by memory loss or something, then it's harder to set her up as evil (because she probably doesn't look like she's hiding something).

So, my question is, any advice on how to have her look she's hiding being the villain, without making her stupidly incompetent?

[Gossamer]

Small things, make her forgetful, stuff that she ought to know, like her own phonenumber, when she joined the watchers or something. Maybe what looks like a blood stain on her shirt but turns out to be ketchup or something. And give her another secret that she's shameful about and trying to hide, maybe she's an otaku or a Justin Bieber fan despite her age or something. Plus, one or two coincidences, she just happens to be on the scene etc.

[Chaosmark]

I'm going to second Goss with the "other secrets to hide". That ALWAYS gets people riled, because they can tell that you're hiding something, and naturally assume it's the worst thing imaginable.

[Ancient Gamer]

Let the Demon be of the sadistic kind, stalking her, killing people after she has met with them. If the Demon's behavior starts just as she arrives in town, she would be a prime suspect. After all, everyone she speaks with winds up dead.

[Dragonlordmax]

There's some good advice here which I will be using, but I'm not sure it's answering what I was originally thinking about.

I want to have a pre-episode cut scene where it looks like she's ambushing a person (one who looks like a Watcher, preferably), but in truth, it's a demon disguised as a person. I'm thinking Slitheen-style. I want this demon to be the enemy of the episode, or closely related to it, but to make it look like she's the demon, impersonating this other person (the skin thing wouldn't be obvious), as the demon, somehow escaped, pursues its sinister agenda.

Now, I'm thinking the demon is part of some demon group or hive mind or something. NPC kills it for real and takes something from it, something vitally important to the group's plans, perhaps. Now the demons can stalk her to try to recover it. Or maybe she gives it to the Slayer or something, and is being stalked to figure out where it went. Or similar. They can make vague references when caught to some sort of queen, which should go a long ways towards implicating our NPC. Maybe the queen kills people, then births demons into their skins.

Meanwhile, she can be hiding something else, and sort of accidentally irritating the PCs (she's so pretty that the Slayer's boyfriend is interested, she doesn't think much of their exploits thus far, whatever). This should all manage to add up wrong.

The weak point in this idea is, why doesn't she tell people about the thing she found? The obvious reason is that she wants to figure it out herself to "prove herself" or something, but my problem with this is that, in Buffy, where a demon gang could be plotting to end the world, that seems pretty irresponsible. And I'd like to avoid making her look like that (inexperienced would be fine).

So maybe it should be something very innocuous in appearance? Or perhaps she's unknowingly splashed with magic blood or hears some magic words or something?

[Ancient Gamer]

what about making it so that she does tell about everything, but she does it to the wrong person?  Could be an illusion,  a demon or a cultist of some kind.