"Come over. Stefan having a fit."

It's the kind of text Elena gets from Damon all the time. Usually "Stefan having a fit" actually means "Stefan's not letting me kill someone I really want to kill", but still. Elena goes to the boarding house without thinking twice.

It's not until she walks in and something slams the door shut behind her and pins her, facefirst, against the door, that she remembers that Katherine is living with them right now.

"Damon forgot his phone," Katherine says against her ear. "I decided to have a little fun."

Elena forces herself to stay still and calm. Not that it matters; Katherine can probably tell that what she wants to do is scream and panic. "Katherine. What do you want?"

"Oh, plenty of things. The moonstone. Stefan." Katherine puts a hand on her hip, squeezing painfully. "A certain doppelganger out of my life."

"If you kill me, Stefan will be pissed. And the deal with Elijah will be off."

"I'm aware of that." Katherine's hand slides down to her thigh. "If I wanted you dead, you'd be dead."

Elena can't stop her breath from catching. Especially not when Katherine leans forward and brushes blunt human teeth over her neck. No way. No way, not even Katherine is this crazy, not even Katherine...

"If you cooperate," Katherine says, "I promise to be very nice." She takes a step back and turns Elena around. Elena closes her eyes, out of self-defense more than anything else. Maybe if she just looks really, really not into it, Katherine will leave her alone.

Then again, Katherine's completely insane, so probably not.

"Elena." Katherine manages to make her voice both coaxing and sarcastic. "Open your eyes." She slides her hand up Elena's thigh, up her side, fingers brushing the side of Elena's breast before settling on her neck. "Open your eyes or I'll break your neck."

Elena opens them. Katherine's smiling.

"I really, really hate you," Elena says.

"The boys don't have to know."

Elena's not sure why Katherine's even trying to convince her. She's not going to agree, and Katherine can force her to do whatever she wants, and knows it. "I hate you," she says again.

Something passes over Katherine's face, a savage expression that makes Elena want to run, and then they're kissing.

It's not good, because Katherine's crazy and is forcing her to do this. But it's - Elena doesn't know. It's dangerous, and at this point, Elena shouldn't be surprised that kissing a sociopath is enough to kind of turn her on.

"No," she says the second Katherine pulls away. "Katherine, don't make me do this."

"Oh, I'm not going to make you do anything." Katherine turns away, walking out to the living room. Elena doesn't try the door; Katherine locked it, and can speed over and stop her if she tries. She stays very, very still instead, as Katherine strips off her shirt and then unhooks her bra.

There's no reason for her mouth to go dry, Elena thinks furiously. She knows what Katherine looks like. They look exactly alike, for God's sake.

"You could ask me, though." Katherine turns around. Elena looks away. "Ask me to do it."

"Why?" Elena knows she sounds borderline crazy, angry and on the edge, but she can't stop herself. "Why should I ask you?"

"Because if you do, I might stay in line. Leave your boys and your...family...alone."

The distaste in Katherine's voice is obvious, and it makes Elena hesitate. What if she's telling the truth? If letting her have her weird sex power trip means everyone will be that slight bit safer? "Elijah -"

"Keeps his promises, but interprets them creatively."

Elena can barely think. She can barely think, and Katherine's half-naked, and -

"You have to quit tormenting Damon," she says in a rush. "You have to promise to stop."

"Hmm." Katherine laughs. "Bargaining. You're a piece of work, Elena."

"Shut up and answer me," Elena says through gritted teeth.

Katherine sighs. "Fine. He's boring anyway."

Elena's probably going to hate herself forever for opening her eyes then, looking at Katherine, and nodding. "Yeah, okay."

Katherine's smile is one Elena's pretty sure has never been on her own face. It makes her shrink back against the door, flattening her palms against it as Katherine comes closer.

"Relax," Katherine says, stroking her cheek. "I promise to make it good."

Katherine's breasts are right there. Elena doesn't know what to do.

"You're so young." Katherine sounds delighted. "When were you going to figure out you like girls?"

"I don't," Elena says.

"Hmm, maybe you just like fucking vampires, then." Katherine hooks a finger in the neckline of Elena's shirt - and rips it down the middle. "You should wear that jacked topless. I promise you, Stefan -"

"Don't talk about Stefan," Elena snaps.

"Well, well, well." Katherine pulls her forward and takes off her jacket and then her shirt. Elena tries not to shiver or try to cover herself up. She agreed to this. "You've got a little fight in you after all. I wondered."

"Can we just get this over with?" Elena says. It's obvious where Damon learned how to talk like a cartoon villain.

"Sweetheart, I don't know what Stefan's been teaching you, but it's good to take time." Katherine fists a hand in Elena's hair and kisses her. The hand hurts, but the kiss is gentle, and - yeah, it pisses Elena off. Because this isn't something she wants, this isn't something she's doing because she wants. So she bites Katherine's lip, ignoring the way Katherine laughs a little in favor of shoving Katherine back.

"Upstairs," Katherine says, pulling away. "I'll follow you."

Elena picks up her clothes and goes. Nothing feels real anymore, especially not when they get to one of the spare bedrooms and Katherine locks the door, kissing Elena again and reaching behind her to undo her bra.

"It's interesting, isn't it?" she says, taking a step forward. And - Katherine's topless, and they're pressing together, and she looks exactly like Elena. Elena tries and completely fails not to panic.

"Oh, stop it," Katherine says, and shoves Elena hard, sending her toppling back onto the bed.

"Pants off," Katherine says, taking her own advice.

All Elena can do for a second is stare. Katherine's wearing lingerie that Elena would lay money on being expensive, and - her hand is wandering down until it's pressing against her clit in a way that Elena likes, too.

That's more than enough to get Elena to look away and scramble to obey. She doesn't take her underwear off, either; hers is cotton and boring, and comfortable, thanks. She focuses on how dumb she thinks silk panties are instead of the fact that Katherine's circling over to the bed and then getting on it.

"You're shaking," Katherine says. She reaches out and brushes the back of her hand against Elena's left side, up her ribs, the underside of her breast, and then - Elena can't keep from shuddering when Katherine touches her nipple.

"It's so convenient, knowing what you like." Katherine sounds delighted. She would. Elena's going to respond with something snotty, but then Katherine twists her nipple, and fuck, Elena's into this.

"Good," Katherine says, and moves in a blur. Elena blinks and her wrists are pinned above her head, Katherine pressing her back into the mattress.

"You've gone down on Stefan," Katherine says. She's rocking her hips lazily, rubbing herself on Elena's thigh.

It's not really a question, but Elena nods anyway.

Katherine grins. She looks delighted. "Keep your hands up," she says, and removes her hands from Elena's wrists, bracing herself on the bed instead as she kisses Elena.

Elena has to give herself permission to be into it or go crazy, so she kisses back, noting the way Katherine's hips move, the way Katherine reaches down with her left hand to play with Elena's breasts again. Her movements are fluid, easy, which - so are Stefan's. But it's different, because Katherine's not really being careful with her.

And God, Elena's getting wet.

"That's right," Katherine whispers, moving down to kiss Elena's neck. She bites and sucks, still with blunt human teeth. Elena's pretty sure it's not hard enough to give her a hickey; Katherine will want this to be a secret. "God, our body's so responsive, isn't it? It's so easy to...enjoy." She slides her hand down Elena's stomach, just brushing the top of her underwear.

"This would probably be easier to enjoy if you talked less," Elena says. She sounds stupid, breathless.

"Mmm, but would it really?" Katherine kisses Elena's right nipple, then sucks it. And, yeah, Elena's sensitive, and Katherine knows exactly how much pressure to apply, exactly when to pull away. Elena's determined not to make stupid sounds, but she can't quite stop herself from moving her hips restlessly. The hand hovering at her hipbone is a stupid, annoying tease. Like everything about Katherine, she thinks wryly.

"Probably," Elena says, but she doesn't sound convincing even to her own ears.

"We'll see." Katherine moves down to her stomach. It's been obvious where she's going, but Elena can still barely breathe as Katherine eases her underwear down. "I could have made you come just playing with your tits. You would have loved it."

"Okay, I get it, we have the same body," Elena snaps. "It's not actually that hot."

Katherine smiles up at her. "You don't really believe that," she says, and kisses the inside of Elena's thigh, shoving her legs farther apart unceremoniously.

Elena really, really hopes Katherine doesn't try to make Elena eat her out. "It's physical."

"And you're physically into yourself." Katherine traces a single finger around Elena's clit, then lower, trailing it along her folds. "It's a bad idea to lie to someone who can feel how wet you are, Elena."

Elena closes her eyes and rocks her hips. She's not sure if Katherine's tone counts as seductive when they're - like this.

"Good girl," Katherine says, and leans forward, dragging her tongue over Elena's clit.

It's too much, too soon, which makes it exactly right. Elena shakes a little with the effort not to move, devoutly grateful when Katherine switches to light, teasing pressure. Elena keeps her eyes closed, focused on how it feels, trying to pretend it's someone else - except she can't, because no one else would be this good at it. Not even Stefan. And she can't stop picturing how Katherine must look, sucking her clit lightly, just barely pressing a finger into her and then backing off again. How she's probably concentrating and laughing at Elena at the same time, how wrong this is.

"That's right," Katherine says when Elena moves her hips a little. "You can move, you know, I'm not going to break. Stefan rides you, doesn't he? I know I taught him how."

"That's none of your business."

She feels it everywhere when Katherine laughs. "If you say so," she says, and pushes a finger into Elena.

"Oh, God," Elena says without thinking, and arches her hips. Katherine moves with her, focusing on her clit as she fucks her slowly.

"Good," Katherine says. "God, you look good. Tell me you've gotten yourself off with a mirror around, Elena. Stefan used to tell me I looked like a doll." She slips another finger in, moving them in tiny circles.

For a second she's quiet, too busy licking and fucking Elena. But then she says, "He loves that we like getting fucked. He loves when we spread our legs, asking him to move harder. If you beg for him, he'll love that." She punctuates the statement with quick, hard movements of her fingers.

Elena hates the talking. She doesn't want to think about Stefan. So she opens her eyes, mostly in self-defense - and then moans, eyes stuck on the image of Katherine eating her out, staring up at her exactly like Elena thought she would be.

"You want it harder," Katherine says. It's not really a question, but Elena nods.

After that her world is nothing but feeling, Katherine's hand and mouth and fucking talking, and it's all Elena can do to hold on, until Katherine presses in hard and crooks her fingers and then she just can't anymore.

When she comes, she bites her lip to keep from crying out. She doesn't miss the way Katherine gentles her movements, stroking her through it, or the way Katherine brushes her teeth against her thigh. The thought - the knowledge that she could bite - sends her off again, and when she finally comes back down, the first thing she registers is Katherine laughing at her.

"Easy," Katherine says. Elena opens her eyes to glare, but winds up moaning instead, because Katherine's licking her fingers and looking incredibly pleased with herself again.

"I could get you off again," Katherine says. "I could spend all day with you. You have no idea what this body is capable of." She brushes her still-wet fingers over Elena's stomach. "Now it's your turn."

Elena swallows hard. She doesn't want to, but Katherine moves over beside her, and she knows she doesn't have a choice.

"I'm not going to make you eat me out," Katherine says, and Elena tries and totally fails not to be slightly disappointed, along with relieved. "Just use your fingers. You know what we like."

She does. And it's...well, it's awkward and weird, and she's not that great at it, from this angle. But she likes being above Katherine, likes knowing how to make Katherine close her eyes and get wetter. Katherine's putting on a show, but she's not faking how into it she is, and Elena knows it.

It doesn't take long to make her come. Which, okay, so Katherine's into eating girls out. That doesn't say anything about Elena. What does say bad things about her, though, is the way she can't stop staring at Katherine comes, and the way she cries out delicately, hands tearing the sheets as she pumps her hips.

Elena knows she's bright red, but...God. She's hot, she really is.

Katherine smiles smugly when she comes down, then gets off the bed, blurring over to her clothes and getting dressed. "I'll leave you to get yourself put back together," she says. "Good luck finding another shirt."

Elena doesn't even try not to roll her eyes. "I have some in Stefan's room."

"Oh, I know." Katherine opens the window. There'll be a smell, Elena realizes, and blushes. "Oh, and Elena?"

"What," Elena says flatly. The embarrassment is setting in.

"I don't keep my promises."

Elena's mouth falls open and Katherine laughs. And then, just like that, she's gone.