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!

Second IMPORTANT Author's Note: New and revised!! Sorry it took so long for me to update. Please review! Enjoy!

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Buffy hung up the phone and turned around to look at the gang, "Damn". She sighed heavily and plopped down next to Riley. She aggressively pulled her long, blonde hair up into a messy ponytail. She put her head on his shoulder as they group gave her a quizzical look.

"My lovely twin, Kathryn," Buffy sighed again, "Yes Xander," she added after seeing the look of joy and ecstacy on his face, "the hot one."

At this Anya smacked Xander on the arm and proceeded to talk, "Well if they're twins they must look the same." Buffy smiled, thinking Anya was being awfully nice, until she continued that is, "And if they look the same I sure don't see why you would… I mean look at her."

Xander's eyes widened in horror and slapped a hand over Anya's mouth. He turned to Buffy, "You're beautiful Buff."

"Yeah, you are," Riled stated, kissing Buffy's head.

Willow shrugged at Buffy as Tara walked in. Tara sat down next to Willow and asked, "What's up?"

"Attack of Miss-I-Don't-Know-When-to-Shut-the-Hell-Up," Willow answered, inclining her head toward Anya.

"Hey-" Anya started.

"So, Buffy," Riley cut her off, "What'd your sister want?"

"Sister?" Tara questioned, wrapping her hair around her finger. "You have a sister?"

"Twin actually," Buffy supplied, "Kathryn Merteuil. She stayed with dad after the divorce."

"Merteuil?"

"Yeah, that's my dad's last name. Summers is my mom's maiden name. We both took it after the divorce. She just called a few minutes ago."

"Okay, so what did she want?"

"Well it turns out dear old dad got remarried. Didn't bother to tell us of course. So my new step mom is some cheesy ex-debutant, probably already sleeping around with the pool boy, with daddy watching on, oblivious. Oh, the icing on the cake? I gained a new stepbrother, Sebastian Valmont."

"Sebastian? Like the singing crab from The Little Mermaid?" Anya asked, perking up.

"Yes Anya, I'm sure he's that same dazzling shade of red too," Buffy snapped back.

Xander snorted a laugh and pretended to cough to cover it up.

"Oh, there's a cherry on top… they're in town. I guess dad called my mom and asked if Kathryn and Sebastian could stay with us while he and his new wifie go on an 'extended honeymoon'. I just love how much my mom shares with me."

"When are they showing up?" Willow asked.

"Tomorrow," Buffy groaned, "at noon."

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"This is it?" Kathryn snapped, setting her bags down and looking around the Sunnydale airport. She perched her size two frame, swathed in a Gucci wrap dress, on one of the old plastic chairs. "Fuck."

"At least we're not there anymore," Sebastian stated, sitting down on another one of the plastic chairs. He fiddled with one of the buttons on his Armani blazer.

"You only wanted out of there because Ronald was pissed off about Cecile."

"Yes… and how could he have found out I wonder… " Sebastian said sarcastically, eyes boring into Kathryn.

Kathryn shrugged, smiling sweetly.

"Is that them?" Sebastian questioned, looking toward the entrance of the lobby.

Kathryn turned and saw Buffy and Joyce walking toward them. "Fuck me," she sighed deeply and then instantly perked up, "Mom! Buffy!"

Sebastian laughed to himself and thought, She is so fake. He stood up as Joyce and Buffy hugged Kathryn.

"Sebastian Valmont," he said, extending his hand once they were done.

"Joyce Summers," Joyce spoke warmly, her brown eyes sparkling happily.

"Buffy," she said, not sounding the least bit interested, "Guess you're my new… er… brother."

"Stepbrother," Sebastian corrected her, "Not blood related."

Buffy laughed cautiously. Sebastian cocked and eyebrow at her. She was quite different than Kathryn. Her hair was long and blonde, instead of dark brown and the shorter cut Kathryn favored. She didn't appear to insist on wearing expensive designer clothes to make sure she stood out in the crowd. Her eyes were warm where Kathryn's were mostly cold. She also laughed, which wasn't one of Kathryn's favorite things to do. Her handshake was also surprisingly strong.

"Best get to the Land Rover before something happens to it," Joyce smiled.

Sebastian inwardly groaned and wished he had his beloved Jaguar.

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"Sure I'll keep an eye on him cuz," Gunn said into the phone, "No problem man."

Angel walked in as Gunn hung up the phone, "Who was that?"

"My cousin, Ronald. Needs me to keep an eye on someone. Mind if I'm out of town for a bit?"

"Sure, we should be able to hold the fort down."

Gunn nodded, picked up his Adidas sports bag, and headed out to his truck.

"Sunnydale here I come," he said, starting the engine, not knowing who Buffy was and how she could be tangled up in this.

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"Uh, this is Willow, Xander, Tara, and Anya," Buffy said gesturing to each respectively.

They all muttered a greeting to a bored looking Kathryn and slightly amused Sebastian. Kathryn took in the group. The redhead – Willow, was it? – was apparently into the whole environment thing or something, considering she was wearing what looked like some organically made shirt. Kathryn shuddered, Crunchy Xander kind of made her think of a male Cecile, but maybe a little more sexually inclined. One would hope. Tara was dressed similarly to Willow and had an amulet around her neck. Anya beamed up at her and appeared to be eyeing her purse as well. Kathryn instinctively pulled it closer. Anya then turned to look at Sebastian.

"He's not red," she stated matter-of-factly.

The rest of the Scoobies looked horrified while the newcomers looked confused.

Buffy quickly changed the subject, "Wanna see where your rooms are?"

Kathryn and Sebastian followed Buffy up the stairs. Buffy walked to the spare bedroom, which was decorated with fleur-de-lis print, and said, "Sebastian you can stay in here," Kathryn elbowed him and snickered, "and Kathryn…" Buffy trailed off and walked through the bathroom that joined her room and the guest bedroom, "you can stay with me." Kathryn's eyes took in the old New Kids on the Block posters and butterflies that were on the walls. She saw collages of pictures of the gang over the years. She looked at Buffy's bed, which differed a lot from hers, crocheted pillows and all. She then looked to the cot in the corner of the small room and her eyes narrowed, "Is that mine?" Buffy nodded at her and forced a smile. Kathryn's stomach turned, It's probably polyester. Damn.

Sebastian smirked at the anger that was plastered across Kathryn's face. He turned and looked at Buffy, who was standing there as if unsure what to do. He never would have guessed they were sisters… except for the whole twin thing. Kathryn was such a bitch and Buffy was… well, not.

"I'm starving," he said, breaking the silence.

"Oh!" Buffy said, coming to life, "Follow me."

As they walked down the stairs they could hear the gang chatting in the living room.

"An… I can't believe you said that," Xander sighed.

"What?" Anya questioned.

"Miss Motor-Mouth strikes again," Willow said flippantly.

Buffy shook her head and went to go into the kitchen, but before she could the doorbell rang. She quickly walked over to the door and opened it. Riley stood in the doorway. He kissed Buffy and followed her into the kitchen where her… siblings… had found some food. Kathryn looked at the warmed up macaroni on her plate with distain. Sebastian was perched on a stool eating chips out of a bag.

Kathryn perked up when she saw Riley and touched her hair, "Who might this be?"

"My boyfriend, Riley Finn," Buffy told her.

Kathryn's face visibly slackened. Sebastian looked at her as if to say "Always the little twits?".

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Buffy and the gang were sitting at a table in the Bronze. Kathryn and Sebastian had gone to the bar.

"Buffy… he's pretty damn hot," Willow noted and quickly shot an apologetic look at Tara.

"This coming from you," Anya added.

"Anya, would you just shut up?" Willow fumed.

Xander, noticing the tension, got up and drug Anya onto the dance floor.

"What's up with you and Anya?" Buffy asked Willow, taking a sip of her pink drink.

"She's just been extra… I dunno… Anya-ish lately." Willow shrugged, "So about Sebastian… "

"You mean my stepbrother."

"You're not blood related stepbrother. Yes, about Sebastian… "

"What about me?" he asked, smiling as he and Kathryn sat back down. Kathryn straightened her Louis Vuitton black pleated skirt and smirked at Buffy, challenging her.

"Um, uh… " Buffy tried and glanced at Willow, who shrugged, "Wanna… er… dance?"

Sebastian seemed to be taken by surprise, but nodded, "Sure."

They got up and headed out onto the dance floor. Buffy thought it would be odd dancing with Sebastian, but it wasn't even as if he was her stepbrother.

Not blood related, she told herself, just as the others had, Besides, I'm with Riley, so it's not like I'm with him. But why am I slightly happy Riley's not here?

"You're so tense sis," Sebastian echoed what he had said to Kathryn not so long ago.

"What?" Buffy asked stupidly, thrown off by Sebastian calling her "sis".

"Are you okay? You seem tense."

"Oh, just a lot on my mind," she said, just realizing they didn't know she was the Slayer and that she was going to have to sneak around again.

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This is pathetic, Buffy thought to herself while sneaking around and trying not to wake Kathryn, who was zonked out on the cot with a mask over her eyes, I haven't had to sneak out since junior year.

She quietly let herself out of the room and snuck down the stairs. She slipped on her zip up hoodie and headed out the door. She jogged down the street and headed toward the docks. She looked around cautiously for any sign of movement. She saw something move to her right and she ran after it.

Buffy chased the creature until they reached a chain link fence. She cornered the fledgling, probably just in high school judging by its clothes and look of superiority, and quickly staked it. When she brushed the dust off of her she looked down and saw a glowing, yellow orb. She knelt down to pick it up when she heard a voice behind her.

"There's no rave here missy. You should go before the cops come," an overweight security guard in a old, faded, blue uniform told her, shining a flashlight into her eyes.

Buffy squinted at him and said, "Sorry… my bad. So many parties, so little time."

"What's that?" he asked, gesturing toward the orb.

"Oh you know… typical rave light thing-y."

He shook his head and walked away. Buffy looked at the orb quizzically and wondered to herself, What exactly are you?