Title: Of Keys, Slayers, and Cruel Intentions

Author: Gabby

Summary: Instead of the monks making Dawn the key, Kathryn Merteuil is created to be Buffy's twin sister. And what happens when the handsome Sebastian Valmont is thrown into the mix? Spoilers for seasons 1-5 and Cruel Intentions.

Rating: R

Disclaimer: Not mine. All Buffy is owned by Joss Whedon. And Cruel Intentions is owned by…some other brilliant person who's name I don't know off the top of my head.

Author's Note: My first Cruel Intentions story, but definitely not first Buffy, first crossover, or first fanfic! I'll update as often as possible, if I don't it's because school or something interferes, I have the whole plot and story line down… it's just typing it and getting it posted. Feel free to leave comments and constructive criticism, but please no flames. Enjoy!

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Buffy paced her room, unsure what to do. What the… what the hell does she think she's doing? Spike?My goodness. What does he think he's doing? Oh geez…

Buffy flopped down on her bed and buried her head in her pillow. She then opened her mouth and screamed. Even though the sound was muffled Sebastian heard her downstairs. He set down his journal and walked up the stairs. He peeked into her room quizzically. He saw Buffy's blonde hair splayed across the pillow and her face practically glued to it. Sebastian walked over and sat down on the edge of the bed. He tentatively touched the small of Buffy's back.

"What the!" Buffy shot up off of the pillow; make up smeared on her face.

Sebastian put his hands up defensively, "Sorry… are you okay?"

"Do I look okay?" Buffy snapped at him.

"Um… "

"Exactly! Now if you'll excuse me," Buffy jumped off of the bed, grabbed a pair of pajamas and stalked into the bathroom, slamming the door behind her.

Sebastian stood up and muttered "That time of the month?" and walked calmly out of the room and back downstairs to his journal. He eventually fell asleep on the couch and was only awakened when Kathryn snuck, not so quietly, into the house.

"Now, where might you have been? Hmm?" Sebastian asked, smirking.

"Wouldn't you like to know?" a rather disheveled Kathryn answered.

"Buffy's in a rather pissy mood, so try and be nice when you go up there."

"What's got her knickers in a twist?"

Sebastian cocked an eyebrow, "I'm sure you know."

Kathryn "humphed" and headed off upstairs. She found Buffy sitting on the edge of her bed, staring at the door. Kathryn smiled, "Buffy."

"And how was your night?" Buffy sneered.

"Not very eventful."

"So that make out session was just a fluke?"

Kathryn gasped, "What… ?"

"Oh, I saw you and Spike going at it. Playing tonsil hockey. Don't act like you don't know what I'm talking about Kathryn. What do you think you're doing?"

"Why is it any business of yours? It's my life; I control it, not you. All you've succeeded in doing so far is getting in the fucking way."

Buffy spluttered, "I-i-in the way? All I've done is go out of my way to make you comfortable. I'm sharing my matchbox sized room with you, I'm making sure you don't get bored to death, and I'm putting up with your bitchy-ness. I don't think I could do more if you asked me to."

Kathryn was in shock; her sister had just told her off. "Well… why does it matter anyways that I'm with him?"

"You don't know what he is."

"Excuse me?"

"Nevermind."

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Spike was walking back to his crypt when he sensed someone, or something, behind him. He whipped around quickly and saw what was following him.

"Oh blood hell, what do you want?" he snarled.

"Blondie Bear," Harmony snapped, "What on earth were you doing with the Slayer? And what was up with her hair?"

Spike laughed, "The Slayer? No way… that was her twin sister," Spike put on a high pitched voice, "Kathryn".

"Who cares. What were you doing with her?"

"I'm just trying to get to the Slayer. Besides, why do you care Harm? It's over."

Harmony sneered at him, "I'll get to the Slayer before you."

"Pfft, you're not even competition."

"Oh, you'll see Spike," she spat, "You'll see."

Harmony started stalking off and Spike called out, "Who's gonna help you, love?"

"My minions!"

Spike snickered to himself and muttered, "Harmony. Minions. What's next, pigs flying?"

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"Okay boys," Harmony stated, hands on her hips, "We're gonna capture and kill the Slayer."

"We are?" one of them asked dumbly.

"No Peaches, I just said that," Harmony hit him upside the head, "Yes we are!"

"How?"

"We're gonna kidnap her sister."

"She has a sister?" one of the others asked stupidly.

Harmony sighed, "A twin sister."

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Sebastian and Kathryn were sitting in the living room, watching TV, when a brick came flying through the window. Kathryn screamed and dove behind a chair. Sebastian slowly stood up and walked over to the brick. A note was attached. He pulled it off of the brick and opened it. In big loopy letters it read "Come on out Slayer".

"Slayer?" Sebastian looked confused, "Like that one band?"

"What was that?" Buffy yelled, running down the stairs.

Sebastian shrugged and pointed at the brick. He then handed Buffy the note. Buffy read it and looked at it quizzically. That's when they heard a voice from outside.

"Come on Buffy! I know you're in there!"

"Harmony?" Buffy asked, incredulously.

"Never thought you'd see me again huh?"

Buffy sighed, "Wish I didn't have to. And who are the other vamp-" Buffy stopped herself, "Who are the others with you?"

"My minions."

At this Buffy laughed until she cried. Sebastian looked at her in confusion. And all the while Kathryn had snuck out of the room, hoping to go find Spike. She walked to the back door, only to be caught by one of Harmony's "minions". He put his hand over her mouth before she could scream and drug her off into the night.

Harmony saw that Peaches had caught Kathryn and smirked at Buffy, "See you later, Slayer." She and the rest of her entourage then stalked off.

"Slayer? What-" Sebastian was cut off by Xander and Anya running into the house.

"What's up guys?" Buffy questioned.

"Harmony." Xander gasped, "Has. Kathryn."

"Shit."

"That little blonde girl?" Sebastian asked, bewildered.

"Oh, she's not just some little blonde girl," Anya stated, "She's a vampire."

Buffy, Xander, and Sebastian stared at her in shock; Sebastian's reason completely different than the others.

"She's kidding of course!" Xander practically shouted.

"I have to go get her," Buffy said.

"I'm coming with," Sebastian spoke boldly.

"Oh no you're not sparky," Xander chided.

"Xander… I think he should," Buffy muttered, "It's time. You and Anya watch the house, we'll be back."

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"What the fuck do you want?" Kathryn asked, hanging limply from the wall.

"To show Spike I'm just as good as he is," Harmony snarled, "And to get the Slayer."

"Spike? What does he have to do with this?"

"Blondie Bear has to do with everything."

"Blondie Bear?"

"While this is a thrilling conversation, can we just get to the killing?" Buffy asked, walking into the room, Sebastian in tow.

Sebastian looked rather frightened with a cross in his shaking hand. His other hand was clutching a vial of holy water. His face was the color of printer paper. His heart was in his throat and he thought he'd pass out any second. The room was filled with people whose faces were distorted; one of his sisters was chained to a wall, while the other was wielding a rather nasty looking axe.

Kathryn's face morphed from one of fear into one of shock and awe when she saw her sister and brother enter the room. Buffy was holding a silver axe that glinted when the light hit it correctly. Sebastian looked like he was about to wet himself. If Kathryn herself wasn't so scared she probably would have laughed at him. She looked at the group surrounding her. Their twisted faces looked at her with hunger. She had no idea how Buffy was going to fight them, considering they had super strength. She learned this when they chucked her across the room and into a wall. There's no way her petite little sister could save her. They were all dead.

"Peaches, watch the girl," Harmony pointed at Kathryn, "I'll get Buffy."

"Wait… " Peaches drawled.

"What?"

"Which ones which?"

Harmony sighed, "If we had the Slayer chained to the wall do you really think I'd be fighting her right now?"

"No… "

"Exactly! Now watch her!" Harmony pointed to Kathryn again.

Harmony sauntered over to Buffy and looked her in the eye. Buffy's eyes narrowed and she quickly lashed out at Harmony, hitting her over the head with the axe. One of Harmony's lumbering lackeys ran over as he saw her fall to the floor. He ran at Buffy and knocked her to the ground. They wrestled and he wound up getting the axe from her, but before he could do anything Buffy kicked him in the stomach and he went flying. She jumped up and saw a wooden unicorn from a carousel among the plethora of unicorns that decorated the room. She ran over and broke it into a few pieces. Buffy threw one at Sebastian's feet and yelled, "If one comes at you, stake it!" She ran over to the vamp who stole her axe, who was now standing up, and kneed him in the groin. He howled and dropped the axe. She glared at him, "Ass," then quickly staked him and then picked up her axe. With a stake in one hand and an axe in the other she ran at the vampires who were guarding her sister.

Kathryn was struggling against the chains and the vampires leered at her. Buffy quickly attacked. While she was fighting them Harmony had gotten up and made her way over to a very scared Sebastian. He fumbled with the stake and wound up dropping it. Harmony kicked it away and growled, "You broke my unicorn." Sebastian shoved the cross in her face and as she backed away he threw the holy water at her. He heard steam hissing as the water burned her skin. Harmony shrieked and punched Sebastian in the jaw. He fell to the ground and didn't move. Harmony bent down to pick him up.

"Hey!" Buffy called.

"What?" Harmony snapped and looked up.

"Missing something?" Buffy held up in her hand the horn of the unicorn.

Harmony was about to retort, but quickly looked around. She noticed all her minions were dust. She backed up towards the door, "Until next time, Slayer," and took off.

Buffy sighed and broke Kathryn's chains, "Some people never change."

"Who were they?" Kathryn questioned.

"Vampires."

"And you… hunt them?"

"Something like that."

"Are there a lot of them?"

"You betcha."

"Have I ever met one before this?"

"I'd say so. Goes by the name of Spike."

Kathryn quickly shut up and followed Buffy as Buffy went over to Sebastian. She lifted him up easily and started out the door. Kathryn followed her like a puppy would its master.

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Author's Note: Hey! I know that this actually happens before Riley leaves and what not, but I reworked stuff… it seemed to work out better for my story. Thought I'd just point that out. Hope you're all enjoying it so far!

VikGlad you like it! There'll be more about Spike and Kathryn's reaction to what he is coming soon, don't worry.

Lifes-Slayer: I love the movie too! I'm addicted. Haha. And I'm not sure about Annette, I wanted to… but I'm trying to figure out how to work her in. If you have any ideas, let me know!

Allen Pitt: I was definitely in the "Riley Can NEVER Replace Angel" group. So… he's mostly doomed for me. And after your last comment… it sounds like this chapter was your kind of chapter. :-D Hope you enjoyed!

Softly descending: Thanks for reading! And I'm gonna hopefully work Angel into it more… still trying to work it all out.

Chosenfire28: Yeah, Kathryn doesn't seem to be doing herself much good. We'll see if she changes (or not) after all of this… hmmm. Thanks so much for reading!