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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"So how was your 'chat' with our sister?" Sebastian asked, flopping down on the couch.

Joyce had gone to work at the gallery and Buffy had run off somewhere, so the two had the house to themselves. Kathryn primly sat down on a chair and cocked an eyebrow at Sebastian. Seeing the look on his sister's face Sebastian sat up, "What?"

"Well, she now knows of your sexcapades," Kathryn said, voice smooth as silk.

"You told her?"

"Of course I did, darling. It wouldn't be fair to leave her in the dark now would it?"

Sebastian glared at her and pushed himself off of the couch. He stalked over to the stairs and started up them. Kathryn turned around in her chair, "Going off to write in your precious journal?"

Sebastian continued up the stairs without looking back at her.

"Could you be anymore gay?" she spat.

"Bite me," he growled back.

"Gladly."

Kathryn waited a few more moments until she heard the door slam. She sighed contentedly and quietly, to no one in particular, said, "We'll see Sebastian, we'll see."

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"You have siblings?" Spike asked incredulously, following Buffy through the graveyard.

"A twin sister and step-brother, yes. Now can you leave me alone?" Buffy said through clenched teeth, resisting the urge to stake him right then and there.

"Well, well, well… a twin you say?"

Buffy rolled her eyes, "You're almost as bad as Xander. Why are you following me? Leave."

"Can't a bloke help out a friend in need?"

"Friend? Spike, I'm the Slayer, you're a vampire. The only thing you should be getting friendly with right now is Mr. Pointy, here."

"Well Angel's being a vampire didn't stop you from getting friendly. More than friendly… shagging all the time."

Buffy stopped dead in her tracks and turned to face him, fuming, "Don't you dare talk about Angel. You have no right. Besides, he was different."

"Oh yes… that soul of his. Just peachy isn't it? Aside from the fact that when he gets all happy inside he turns into a bloody mass murderer."

"Isn't that what you are?" Buffy stated coldly.

"Chip, love, remember?" Spike said, patting his head.

"Oh yes, so you won't react when I do this?" Buffy then punched him in the jaw, "Stop following me."

Spike touched his jaw, scowled at her, "Bitch," and walked away.

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"Good morning," Sebastian said cheerfully as he entered the kitchen.

"Mhm," Buffy responded, rather coldly.

The cold shoulder? What could Kathryn have told her, exactly? Sebastian asked himself.

"I was thinking," he voiced out loud, "that we could maybe go out for lunch today?"

"I dunno. Might have stuff to do," Buffy answered.

"That's not a nice way to show your guests around," he chided, "Besides I talked to Joyce, she says you're free."

"She would."

"Oh, rather hostile now aren't we?"

Buffy shot him a look, "Where's Kathryn?"

"Getting her 'beauty sleep'."

Buffy laughed at this. She looked at her 'brother'; he really did seem to genuinely want to have lunch with her. She sighed, "Fine, but Riley's coming too."

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The three of them sat down at a table at the Espresso Pump. The boys seemed less than thrilled to have the other one there, but tried not to show it. When the tall, skinny, boy with acne came over to ask for their orders Buffy ordered a red eye, knowing that this lunch was going to be a long one. The boys ordered drinks and sandwiches.

"Aren't you hungry?" They both asked Buffy at once, followed by threatening glares at each other.

"Not really," she answered, feeling the knot in her stomach clench even more.

"So how long have you two been together?" Sebastian asked.

"Nearly a year now," Riley answered with pride.

"That's a long time, congratulations."

"What's the longest one you've had?" Riley asked snidely.

"Not entirely sure to tell you the truth."

"So you're that kind of – " Buffy slapped Riley's arm and he stopped, looking sheepish.

Buffy smiled at him and he added, "If that bruises… "

Sebastian smirked, "She a hard hitter Riley?"

"She's stronger than you'd think," Riley answered coolly.

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"I have to go out for a bit," Buffy stated, heading for the door.

"Again? Why so late?" Kathryn questioned, not really caring.

"I… I need some fresh air."

"Let me come with you," Sebastian said, standing up, "Can't be safe for you out there by yourself."

Buffy laughed, "You'd be surprised. But no, you should stay here."

"Too bad, I'm coming with," Sebastian grabbed his coat off of the hook and went out the door.

Buffy sighed and headed out the door after him, He better not get himself killed.

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"Do you take walks in graveyards often?" Sebastian questioned.

"It's a hobby," Buffy smirked.

She suddenly heard a rustling to the left. She whipped toward it and saw something move towards them. She shoved Sebastian, who fell to the ground with an "Oomph!" and ran at the beast. When they collided she looked up and saw it was… Spike.

"Bloody hell Slayer, what are you doing?" Spike bellowed.

"Shh! Keep it down," Buffy growled.

Spike saw Sebastian's form on the ground, pushing himself up. He looked at Sebastian for another second then realized who he was. "He's your brother? That bloody ponce? Why he's another Nancy Boy!"

"Spike… "

"What was that?" Sebastian asked, rubbing his forehead.

"I… uh… fell?" Buffy stammered.

"Who is this?"

"This is Spike."

"Spike?"

"He's… in a band?"

Sebastian looked at him curiously and could have sworn he heard him mutter something that sounded like "Nancy Boy hair gel".

"Well, we should be getting home, Kathryn's waiting," Buffy spoke.

"Oh, she'll be fine, besides I just met your friend here," Sebastian replied.

"No, get on home. I'll stop by sometime," Spike supplied.

Gosh I hope not, Buffy thought to herself.

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"Damn," Buffy muttered, taking off her coat and realizing she forgot Mr. Pointy at the graveyard, "I'll be right back," she announced, putting her coat back on.

When she opened the door Spike was standing there, "What do you want?"

"Hello to you too Summers," he held up his hand, "I found something of yours."

Buffy's eyes widened when she saw Mr. Pointy, "Thanks, well I guess you should – "

"Who's here?" Kathryn asked, walking up to the door. She raised her eyebrows at Spike.

Spike looked at Kathryn and smiled. She was Buffy's twin alright, but with differences. Some subtle, some not so. She was a bit shorter than Buffy and her face was more angular. She didn't have as much muscle as Buffy did, but carried herself well. There was also a colder air about her. She was someone Spike could see himself getting along well with.

"I'm Spike," he said, extending his hand.

"Kathryn."

"Well now that formalities are out of the way Spike should be getting on his way… " Buffy intervened.

"What're you holding?" Kathryn wondered, seeing the stake.

"I'm um… building a little fence?"

Kathryn rolled her eyes at her strange sister and turned back to Spike, "It was a pleasure meeting you. I'm sure I'll see you again sometime soon?"

"You bet, love," and with that Spike was gone.

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"And… and Kathryn said that he was a 'heartbreaker'. Will, I don't know what's going on with this," Buffy sighed.

"Well Buffy, you were the one who said 'But he's my brother. But I'm with Riley. But… but… '"

"But… but… "

Willow smiled at this, but her look then turned somber, "Well his reputation doesn't sound very good. He's probably not one to get tangled up with. And it might get kind of awkward with the whole sibling thing, but then again… no blood relation." Willow smirked at Buffy, "But you can always still look at him."

Buffy sighed, "And Riley."

"What about Riley?"

"He's been, different lately. There's times where I can't… oh, I don't know."

"Stick with him Buff, see what happens. I mean, Tara and I get into our little tiffs, but at the end of the day I know I still love her. And I'm sure the same goes for Xander and Anya."

"Yeah, I guess I just feel like he's hiding something."

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"Buffy!" Spike yelled, pounding on her front door.

"What!" She snapped, opening the door.

"You better come with me."

"Why?"

"Just… please, you need to see something."

Sensing he wouldn't give in anytime soon Buffy agreed and followed him out the door. They headed down to the docks and reached an old, abandoned warehouse. Spike pushed the door open and closed it behind them. Buffy took in her surroundings. The place was dreary and in disarray. It looked as if someone intended on making it into a house, but stopped half way through. She saw a fire burning in a garbage can. She went to ask Spike a question, but he pushed her into the next room. She saw a group of vampires sitting around a human, a seemingly willing human. She shuddered and let Spike usher her up the stairs, planning on taking the vamps out after she saw what she "needed" to see. Spike showed her to a door and Buffy pushed it open. It took her eyes a minute to adjust to the light, but what she saw next would forever be engraved in her mind.

"Riley!" she chocked out.

Riley was lying on the floor with his shirt off and arms extended. There were two skanky looking vampires on either side of him, sucking the blood from his wrists. The blonde girl on the right raised her head and smiled at Buffy, blood on her teeth, "You here to join, sweetie? I'm Sandy."

He looked up at her, and then to the two vampires, "It's not what it looks like."

"Oh… what? So these two very weak, not to mention slutty, looking female vampires managed to capture and sedate you so they could... what?... take turns playing 'Who can drain Riley first?' I'm sure that's what happened."

Before he could say anything she rushed over to him and grabbed Sandy by her hair, hauling her up, "Alright bitch, I'll join your party." Buffy threw her against a concrete wall, which cracked upon impact. Sandy fell to a heap on the floor and started to stand up. Buffy roundhouse kicked her to the head and watched her fly back into the wall. She ran over and staked her quickly in her heart. Buffy's head snapped to where Riley and the other vampire were still sitting on the floor, "You get the fuck away from him." The vampire's eyes widened and she ran from the room.

"Buffy… " Riley tried.

"No!" Buffy pushed past Spike and down the stairs.

She raged into the room with the group of vampires and the human. She grabbed the human by his collar and threw him out of the room, "Get out. Run. Now!" The human stood up and raced out. "As for the rest of you… " she said, turning on the vampires. She grabbed the garbage can with the fire in it and threw it into the room. She watched as it lit on fire and as the flames licked the walls. She heard the vampires' screams and left the building.

"Slayer!" Spike called, chasing after her.

"Why did you show me that?" She growled.

"I thought you should know."

Buffy turned around, looked him in the face and then punched him in the nose, "Thank you."

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"What's wrong?" Sebastian asked as Buffy entered the house.

"Riley. It's over," Buffy stormed off up the stairs and slammed her door.

Sebastian turned to Kathryn, who was listening in the doorway to the kitchen, "And the game begins."

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Author's Note: Thanks so much for the reviews guys! I'm so glad I've been able to update like this… it's really nice! I'll do my best to update as often as possible! Hope you're liking it so far!

LexiThanks! This didn't seem to be a crossover that was often (or at all) done. Hope you continue to enjoy it!

Allen Pitt: You're great. I love the way you think. I think this story and its wackiness will prove to be very interesting… and rather confusing! ;-)

RightsideI'm glad you like it! And stick along for the ride… drama will shortly ensue.

Chosenfire28: Bye-bye Riley:-D

VikThanks!

Thanks everyone!