The day passes without incident; soon it's time to parkour home.

This is, at least, one of the highlights of her new powers.

She's just beginning to descend a lengthy serpentine ramp by jumping from railing to railing when a stranger vaults over the wall and tackles her.

What the hell.

She twists, tries to regain her feet and throw whoever off her.

She manages to send him staggering backward toward the wall he just vaulted over, but he regains his balance and rushes her.

She ducks to the side, trying to grab his arm.

He reacts fast, slipping around her instead of continuing to charge her, and rotating the momentum from his dodge into a spinning kick.

That means he's on one foot when she ducks under his kick and tackles him.

As she hits, he goes so limp that it's like all the bones in his body have vanished.  Exactly like that, in fact - and then he slithers out of her grip like an eerie human-shaped cephalopod.

Ew.

As much as she wants to beat him up, she doesn't know what type of demon he is, and should probably get help...

She starts trying to put distance between them.

He snaps up off the ground like a slap bracelet and takes off after her.  He, apparently, is also quite good at parkour.

She's not perfectly capable of keeping ahead of him, which brings up the question: is he immune to being stabbed with a wooden stake.

Not so immune that he doesn't try to bend his torso out of the way like some kind of weird slug!  The stake ends up sticking him where his lung would be.  Also, the snug athletic wear he's wearing seems to actually be part of his skin.

Maybe technically naked demon for extra creep factor.

She'll yank on the stake but if it doesn't come out she won't get herself trapped pulling on it. And she has other weapons, besides - Giles might disapprove of her bringing weapons to school but Nausicaa is fully aware of how to keep teachers from finding a pocket knife. Like the one she's slashing at him with right now.

He gets cut up pretty bad.  He's not bleeding but it might be that whatever he is just doesn't bleed.  He tries to get his arms wrapped around hers, or around her neck - it's a bit like wrestling with a couple anacondas.

Deep stabs might be the way to go.

She's not really getting tired at least, and he seems less willing to punch her than she's willing to cut him.

She will discover a compact set of internal organs running along his spine that, when hit, will cause him to emit a pained sort of squelching sound, and try to disengage and lope away.

She'll follow at a safe-ish distance. She wants to know where he's going, not bring him down - he's too dangerous for 'interrogating him' to be safe.

He manages to lurk pretty effectively despite it being the middle of the afternoon, sticking to back alleys, and once he thinks he's out of sight, all the detail on his skin and clothes dissolves into smooth shiny grey.  He curls up on the ground, pinching a couple of his deep chest wounds shut, and stays motionless for a few minutes.

She lurks so she can just barely see him. Takes note of his possibly true form.

Apparently, as well as making its skin look like clothing, this sort of demon can give itself natural pockets!  He takes a cell phone out of one, from right where it would be on his leg if he were wearing skinny jeans.

Creepy.

She inches closer, to try and overhear whatever call. Ideally she'd be able to see his phone keyboard, but she knows that's not likely...

His mouth and jaw and neck all turn human-shaped while the rest of him stays shiny and grey, and he begins muttering into the phone.  She can make out "Slayer" and "stabbed" and a disdainful "fuck y-" that signals the descent of his side of the conversation into what sounds like an irritable I-didn't-sign-up-for-this tirade: "look", "my fight, Van-", "not a fucking vampire", "lunatic."

He hangs up, stands, and transforms into a frizzy-haired and much darker-skinned woman before stalking away irritably down the alley.

So he was likely hired by Vanessa. And he knows she's the Slayer.

She follows him, a bit more cautiously.

He, or perhaps now she, emerges from the other end of the alley and gets into a car.