A/N: This is an episode tag / expansion for TW 3x19, "Letharia Vulpina". I wrote it right after that episode aired and posted it on AO3, but forgot to post it over here until now. Oops.

His fingers flutter playfully, almost suggestively up and down the grip of the katana, the wrapped hilt slightly rough, and bumpy to the touch. Scott's just staring at him. Hands gripping the edge of the table behind him, alarm and disbelief on his face. His body shivers just slightly as the reverberations of Stiles' fingers quiver through the long, razor-edged sword lodged inside his chest, piercing him through.

"Okay?" Stiles croons softly, holding up a hand as his other tightens on the hilt. His voice is almost reassuring, as if there's the possibility that things might be all right, that he might be going to pull it out. Scott still doesn't move, just watching him with those dark, earnest eyes that Stiles knows so well. There's the tiniest flicker of hope there, behind the pain and the wariness.

"He's really kind of stupid, your friend Scott. Useful, but stupid." The nogitsune is amused and derisive inside its host's head. It's half thinking to itself, half directing the thought at the boy figuratively slumped behind him and struggling to move with useless, leaden limbs. Everything has gone according to plan and the trickster is brimming over with self-pleasure. Getting to gloat is just icing on the cake.

"No he's not! Leave him alone! Leave him alone!" Stiles shouts at it, the teenager's rage as impotent as the tears streaming down his face. Turned mentally away from him, its attention focused on Scott, the nogistune smiles, reveling in the tingles of pleasure it derives from its host's distress. Stiles hasn't figured it out yet, how much the creature possessing him enjoys the taste of his pain, but he will, eventually.

Stiles watches through eyes that are and yet aren't his own as the nogitsune leans in closer to Scott. He feels his hand tense on the grip of the sword, the wrapping digging into his fingers.

Scott still isn't moving, isn't trying to pull away from him, but there's a flicker of something in his eyes... is it fear? Regret? Horror? Perhaps all of the above, because Scott isn't stupid. He knows what's coming. Stiles can see it on his face, despite the small thread of hope that also still remains. The nogitsune doesn't understand. It doesn't understand Scott like Stiles does. It doesn't understand that that thread of hope and trust is what make Scott strong, even as it makes him vulnerable. And yet, the nogitsune understands enough. Enough to use Scott's trust against him and use his caring heart to manipulate him.

Stiles knows this is his fault. The nogitsune can't exactly read his mind, but it has access to all his memories, all his knowledge of the people around him. Today it even imitated him with a certain degree of accuracy that was sickening. It had hugged his dad while whispering to Stiles the things it might decide to do to him and Stiles had lost it for a while. Not that it mattered. No one could hear or see him now; he was like a ghost in his own body.

"Please don't," Scott whispers, the edge of his voice ragged from the pain burning through him. "Stop." He's begging with those damn, trusting, puppy dog eyes and in that moment Stiles wants with everything in him to jerk the sword out of his best friend's chest and jam it into his own.

But he can't. Instead he reaches out and grips his best friend's shoulder tightly, murmuring again that everything's going to be okay when they both know it's a lie. There's definitely fear in Scott's eyes now and the nogitsune drinks it up, the same way he drinks up Stiles' growing distress as the boy struggles uselessly against what is about to happen. It loves this stage of the game when the host is still so alert, so involved and easily to torment. By the time they're done, by the time he's washed the boy's hands in the blood of everyone he loves, he won't be so much fun anymore. By then the child will be broken, silent and empty. The nogitsune has seen it many times. Stiles won't be as entertaining and delicious then, when he stops fighting, but he will be less work, and anyway, the nogitsune can always take a new host after this one's used up, if it wants to.

With a grin, the nogitsune pulls Scott forward by the shoulder while jabbing viciously forward on the katana, pushing it further into the other teen's body and then twisting.

Scott swallows screams, grunting and groaning in agony as the blade shifts and rotates cruelly within him, cutting and mutilating vital organs. He'll heal, if the nogitsune doesn't end up cutting him completely in half, but it's the worst pain he's ever experienced.

Stiles doesn't swallow his screams. He shrieks at the nogitsune in his head, pounding his mental fists bloody against the figurative walls trapping him, preventing him from getting to the creature controlling him, preventing him from doing anything but go along for the ride. "Stop! Damn it, don't do this! Don't do it! Stop! Scott!"

It's weird and disorientating, the way it feels like he's two places at once. On one hand, it's like he's in a small dark room with the nogitsune wearing his face, looking out through a long window like the mirrored ones in the interrogation rooms at the station and watching the events happening around him. But then on the other hand, he's also looking through his own eyes, feeling his body moving, doing things he doesn't want to do and speaking words he doesn't want to say.

It's like a nightmare that he can't wake up from, only worse because this is real. It sucks that now of course, he could finally tell what was real and what wasn't for a change. He would love to think this was all just a nightmare so he can curl up in a ball, hold his ears and pretend it isn't happening, but he knows better. The nogitsune makes sure he knows better. It had total control of him now. It no longer needs to mess with his memories to erase the traces of its presence. It no longer needed to keep him confused about what is and isn't reality in order to keep everyone from figuring out what is going on with him. The cat - or rather, the fox - was out of the bag now and it no longer needed to hide. So now it reveled in making sure Stiles was aware of everything he was making him do, of every bit of damage he was causing. Because Stiles' anguish was such a sweet, sweet treat to savor.

"Does it hurt?" the nogitsune purrs, speaking through Stiles' body as it continues to twist the blade inside Scott's body. "Hey, look at me. Come on..." he prompts, forcing Scott to look at him. To look at his best friend's face smiling at him as he's gutted. Forcing Stiles to do the same.

Stiles throws himself against the window in his mind. He's pounding on it, shouting, cursing, sobbing almost incoherently. "Scott! Do something! Don't just stand there! Rip it's fucking head off!" Stiles can't understand why Scott isn't changing, why he isn't even trying to fight back. Is he that hurt? Did the sword cut his spine or something?

"Maybe," the creature in his head that speaks to him with his voice and looks at him with a mockery of his own face spares Stiles a second's worth of attention while it tortures his friend. Stiles feels the blade in their hand catch and scrape against bone, grating against something inside Scott's body with a nauseating sensation that makes him want to throw up. "Or maybe ... he just doesn't want to hurt you, Stiles."

"You should have done your reading, Scott..." The sword pushs deeper, making Scott cry out again and the nogitsune all but shivers in delight when Stiles echoes him on the inside. The double-dose of agony he's getting from using the two friends against one another is amazing. "See, a nogitsune feeds off chaos, strife, pain," he explains smugly. "This morning you took it from Isaac, then you took it from Coach, and then from a dying depute. All that pain... you took it all. Now... give it to me." His voice shifts on the last few words, hardly even sounding like Stiles' voice any longer.

The nogitsune grips Scott's head and neck with Stiles' hand, pulling until black veins rise on the werewolf's skin and flow into his own. Ecstasy sluices through Stiles' body as the nogitsune feeds, almost orgasmic in its delight.

It's a sick sensation for Stiles. It's so utterly wrong to feel this much pleasure coursing through him while he watches Scott gasping in his grip, his free hand still twisting the blade in his best friend's chest. Scott, who had backed the twins off him earlier when Stiles knew he probably should have just let them gut him. Scott, who could only be used like this because he tried to help everyone. Scott, who hadn't hesitated to nearly get himself killed trying to protect him from the Oni, despite knowing that he was carrying around an evil spirit that had already killed innocent people. Scott ... whom he would have walked through fire to protect ... and whose blood was now staining his hands.

Scott was family. Stiles would have died for him, but now he was possibly going to kill him and was enjoying doing it. Something painful breaks inside Stiles and the teen slides down the mental wall in his mind - shaking, crying, burying his head in his hands, not wanting to be here, not wanting to have to keep watching this even as he feels his body shuddering in appalling spasms of pleasure.

"You really have to learn, Scott. You really have to learn not to trust a fox." The nogitsune waves Stiles' finger at his shivering victim, his tone and his mood even more playful and pleased now that he's fed. "Hm-m, no, 'cause they're tricksters. We'll fool you. We'll fool everyone."

"Not everyone."

Stiles has been trying to pull away, to not watch, so he isn't entirely sure what's happening when he feels the sharp jab of pain at his neck, but he feels the nogitsune's sudden flare of rage and fear and that gets his attention pretty quickly. His body is crumpling to the floor and everything is starting to go hazy. Reality began to drift as it so often did lately. Is that Deaton? Is he dying? Is Scott safe? Damn, the floor is cold...

"What was that? Was that a cure? Is he okay?" Scott's voice seems to come from far away and he's still inexplicably worried about the friend who just tried to kill him. Don't. Don't try to protect me, Scotty. I don't want to hurt you again. I don't want to hurt anyone.

Stiles doesn't hear Deaton's reply, if there is one, because darkness is descending. His eyes are heavy and his vision blurring away. He blinks and then the world is gone.