This is what should have happened after Caroline killed those witches in 4x17. The beginning is a small recap, the lines directly taken from the episode. The ending is all smut. One shot! Hope you enjoy, please review =)

Caroline had killed. She had watched as the twelve witches dropped one by one. Silas had gotten exactly what he had wanted.
These thoughts swirled around her mind as she watched Klaus dig the graves. She couldn't have felt more powerless, watching Klaus do her responsibility while she sat with tears streaming down her face.
Klaus finished the last grave and dumped in the body. He had way too much experience with death to be strongly affected by it, but 12 was still a large number. His view of Caroline was altered by the murder. He knew her to be capable of anything when it came to her friends, and he still admired her loyalty. However, witches are a valuable resource, one that should not be wasted. Especially considering that all of this was in order to help Silas destroy the veil between our side and the other. Klaus finished replacing the dirt over the witch's dead body and stuck his shovel in the dirt.
"There," he said bitterly, "twelve graves for twelve witches. Like it never happened."
Caroline stood up from the rock on which she had sat and crossed her arms.
"Only it did happen," Klaus continued, "Now Silas has everything he needs to open the gates to hell on earth." He put on his jacket angrily. Caroline really fucked up this time, Klaus thought.
"You were really just gonna let Bonnie die?" Caroline asked softly. How would Klaus have felt if it was Rebekah on the line? Wouldn't he have done the same in her place?
Klaus was angered by her foolishness, and his tone turned coldly sardonic, "I know arithmetic isn't your strong suit, but one is still less than twelve."
"Yeah, but that one is best friend," Caroline's sadness was lit into a fiery rage by Klaus's snide remark.
"Tell yourself whatever you need to so you can sleep at night," Klaus said, speaking clearly, each word intended to stab like a vervain-laced needle.
But he immediately regretted it when all of Caroline's anger was replaced with hurt, her face flooding with overwhelming anguish.
"I just killed twelve people," Caroline repeated, in shock. It was only just starting to sink in. Twelve people's families and friends would be in pain, because of something she had done. Did this make her no better than Klaus himself? Her own lungs seemed to be choking her out, screaming at her for what she had done. They couldn't sustain her breath and she started hyperventilating as her eyes watered once more.
Klaus put his arms around her, and stared into Caroline's sage green eyes, wondering what to do. Had he been less taken with Caroline, more selfish and cruel, he might have pushed her away, as she always did to him. But he picked her up in his arms, and with supernatural speed, Klaus sprinted to the Mikaelson Mansion.
Caroline watched Klaus peel off her dirty clothing. She hadn't slept in over 24 hours, and she was a ragdoll from shock and grief. Her switch was millimeters from flipping, and had she been a weaker person it would already be flipped. But she held on tight to her humanity, remembering how Stefan had been when he was the ripper.
Klaus decided to let Caroline keep her bra and underwear, his emotions were too exhausting to feel anything sexual right now. His basic instinct told him to kill Caroline, she had caused too much damage already, but instead he deposited her inside his porcelain bathtub.
Carolin felt better as she was surrounded by the hot water. Caroline wanted Klaus to stay with her, but she was too embarrassed to ask. Caroline had to watch him slip out of the bathroom and silently close the door.
Klaus stripped down to navy briefs and unbuttoned his shirt. When he woke next morning he found Caroline curled up next to him, wearing nothing but one of his silk shirts and a pair of boxers. Klaus shifted his body to smile at her peaceful face. Dreams are truly a different dimension, he thought.
He slid out of bed and back into the bathroom, where Caroline's clothes remained in a dirty pile. He had to admit he was pleasantly surprised by her light blue thong, but he still threw it in the hamper with the rest of her clothes.
Caroline walked in right after that, yawning widely.
"I should leave, can I get my clothes back?" She asked, her stubborn look back on.
"No, you can't. They're dirty," Klaus said simply. His anger was a rising. After all he had done for Caroline, she wanted to leave? Did she not appreciate everything he had done? You catch more flies with honey that vinegar the little voice in his head told him.
"But I have a fully stocked closet full of women's clothes in the other bedroom, all sizes."
Caroline's jealousy, though she didn't want to admit it, flared. She wanted to think that Klaus hadn't millions of women over the centuries (and she was pretty sure that number was literal), that the accommodations in this house were only meant for her. But when she entered the closet she found dresses, jeans, skirts, and blouses from all centuries and decades, not to mention in all (attractive) sizes.
She grabbed a high waisted skirt and a simple low cut blouse, complete with kitten heels in her size. She also found a dresser full of make up only (which had obviously been recently replenished, in Caroline's experience make up is very perishable), but decided to avoid it in case of any further drama and tears.
When Caroline finally walked back into Klaus's bedroom, the hybrid wrapped her up in his arms and softly murmured in her ear, "Caroline, my love, you look good enough to eat."
Caroline pushed him away, sick of his possessiveness. He had no right to say that to her when he had no doubt whispered the same sweet nothing in many another woman's ear. Caroline may not have been too different from your average beautiful young vampire, but that didn't mean she wouldn't act like it. Because, in the end, what Klaus wanted out of her was sex.
"Did I do something wrong?" Klaus asked.
Caroline gave him a contemptuous glare, "Of course you did something wrong! You killed Tyler's mom, you've attempted to kill Elena more times than you can count on one hand, and now you expect to just forgive that? To just forget all the pain you've caused?"
Klaus's golden eyes flooded with a cold that spread to his entire face and his smile, once sincere, widened to a mocking sneer. "You cannot even begin to comprehend how pathetically hypocritical you are. You just killed twelve of a dying breed. Yes, I am a killer. Yet, I've only killed 8 witches to date, and the world knows no one cares if humans or vampires die. Witches are the most natural, pure thing to walk this earth, and you killed twelve, all in one go! You will enjoy being hunted by their kind for the rest of your immortal life."
"Oh, so I'm so much worse than you? I am sick of your pride and selfishness. You are a horrible hu- thing, right down to your very core. I did what I had to tonight to save my best friend." And with that, Caroline walked out.
Klaus's anger bubbled, but he knew she would be back. Her friends, as naive as they were, would nearly certainly have trouble forgiving her for a crime of this magnitude. "Twelve is still more than one, remember that, Caroline," Klaus called after her in spite.
By the time Caroline left the Mikaelson Mansion tears were flooding her cheeks again, and it was only morning. Caroline ran to the Gilbert house, it felt good to feel the control speed provided.
"Well, well, well, Miss Mystic Falls decided to join us. What could have brought us the good fortune of such a visit?" Damon spent a faux few moments on thought then responded to his own joke, "Oh yeah, the sacrifice of twelve witches."
The Salvatores and Elena sat in the living room. Elena shot Damon a look for his rude comment, but said nothing.
"Caroline... " Stefan started slowly, "We think it would be best if you stayed away for a couple days. Just until Bonnie wakes up and we can get her back to normal."
"Bonnie is-" Caroline started, but was quickly cut off by Stefan, "Asleep, in an upstairs bedroom."
"Caroline, why didn't you break the spell?" Damon asked, enjoying her deer-in-headlights look.
"What spell?"
"The one binding the twelve witches together, maybe? So they didn't all die."
"You know what Damon, I'm not gonna just stand here and take your shit!"
"I'm not going to just stand here and watch you get away with bringing on the goddamn apocalypse!" Damon reciprocated. Caroline expected Elena to say something to Damon but she was quiet. She looked at Stefan, who looked away immediately.
"Well, I'm glad you're happy to have Bonnie back with you!" As Caroline left the house, she thought she heard Elena say her name, but by then she was long gone.
Caroline had no idea what to do. She couldn't go home and face her mother, and she couldn't stay out and cry in public. She had to go back to Klaus. It was her only option.
As much as she despised Klaus, it was the most reasonable conclusion she could reach in her distressed state. So she dashed back to the Mikaelson Mansion.
Klaus threw back another glass of bourbon. It was difficult for vampires to get drunk, alcohol was mostly for curbing bloodlust. Whenever Klaus drank copious amounts of liquor the only effect it had on him was intensifying his emotions. He was angry with Caroline's foolishness. How could she not think that he knew best? After he'd been alive for so many centuries. He was a walking bible of tragic stories, he knew emotions better than any living being. Yet Caroline thought that she had the world figured out. Many a time he had admired her independence, but there is a fine line between independence and pigheadedness.
Klaus heard his front door open and a series of clacking steps. He smiled to himself; Klaus knew she would come back.
"Isn't this a pleasant reunion?" Klaus was sarcastic as ever when he handed Caroline an empty glass and filled it with the golden liquid.
"Good job, Klaus. You've succeeded, my life is a living hell. My friends hate me, you degrade me any chance you get, Tyler is gone."
"Hmm, yes, I do suppose the last one is an achievement," Klaus pushed her further, "And I suppose you can't really call them friends if they hate you. Would 'frenemies' be the proper American word to say here?"
Caroline ran at him in a blind rage. She didn't care how much hurt she received as long as she could cause Klaus some amount of physical pain.
But, him being centuries older than her, the Hybrid was obviously stronger. Laughing darkly, he pushed her up against a wall, securing both her wrists at her head with one hand and leaving his other hand free. Her legs were wrapped around him, but Caroline was still struggling to get free. Just as she was about to unwrap her legs from his torso, Klaus crushed his lower half into Caroline's to keep her secured on the wall.
As Caroline struggled more, Klaus laughed more, "Please love, keep writhing, it's only making me harder."
Caroline let out an involuntary gasp which faded to moan as Klaus's erection pressed into her beneath his pants. Klaus released her arms, though he still mushed his hips to her.
"Aren't you afraid I'll leave?" Caroline breathed.
"By all means, do," Klaus lied, certain she wouldn't. When Caroline stood still, Klaus lifted her again in the same position. She kept struggling at first, but when she felt Klaus's dick dig harder into her she stopped, unable to stifle another moan.
Klaus had her laying on the king size in less than a second. She tried to object when Klaus stripped off her blouse, but Klaus settled any and all concerns by meeting her lips. Caroline twisted her head away, but Klaus only kissed down farther, and when Caroline arched her back from pleasure, Klaus grunted and removed her bra. Caroline attempted to cover up but her arms were pinned by her side.
"This is rape," she barely managed to say.
"Tell me to stop and I will," Klaus replied.
Caroline tried to find the self control to, but failed miserably when Klaus kissed down to her breast.
He sucked on her hard nipple, and when he took it in his teeth she moaned once again. Caroline's breathing was loud and breathy, and a word escaped her lips, "Klaus," she called out. Caroline didn't mean to. She certainly didn't want to, but she did.
"What was that?" Klaus asked as she started panting.
"Nothi- oh," she screamed out as Klaus moved to her other breast.
Caroline ripped off his shirt and ran her fingers along his well muscled torso as her lips met his roughly. Why did he have to be so perfect in everything he did?
Klaus tore off the skirt as well, and licked down to the top of her panties, and going lower.
"No, don't," Caroline said, he voice no louder than a whisper.
"I'm sorry, I can't hear you."
"Don't!"
"Whatever you say," Klaus replied.
Klaus moved back up to kiss her lips, and Caroline arched her back to him again. Klaus didn't know if he'd ever a bigger boner in his life, and he just had to free it. Klaus undid his belt and slid down his slacks. His erection came popping out of his briefs, which he hastily got rid of as well.
Caroline gasped at his naked form, standing at the foot of the bed. Before she could even register how big he was, Klaus lifted her off the bed so her back was to him. He was rubbing his length into her thighs and fingering her through the cotton panties. Caroline didn't know if she could not give in.
Klaus turned her back around and pushed her down on the mattress. Caroline watched as Klaus touched himself, saying her name over and over.
Finally he enveloped her in a long, sweet kiss. She wrapped a hand around his hard on and Klaus groaned, grinning. Caroline rubbed hard, creating a steady rhythm. Klaus held his breath for a few seconds, then came all over the two of them. Caroline sighed and laid back down on the the bed.
Klaus smirked, "You think I'm done?" Caroline's green eyes widened.
He jumped onto the bed and attacked her, passionately meeting his lips to hers. Klaus sucked angrily on her bottom lip and moved his fingers lower, under the only piece of clothing remaining on her body.
Caroline gasped, and her protests died in her throat. She instead sucked on a patch of skin on Klaus's neck, careful not to break the skin considering his blood was venom to her.
Caroline climaxed when he inserted the second finger deep into her, "fuck," she moaned.
Klaus ripped her panties to shreds and flipped her over so she was lying chest down on the bed with her ass still propped up by her knees. Klaus teased her nipple for a while, enjoying the dirty sounds Caroline was making. Then Klaus rubbed his erection against her clit. His length was hard digging into Caroline's wetness.
"Klaus," she managed to utter, "Put it in. Now!"
"Tell me you're mine."
"No."
He took his erection out.
"Ok, ok. I'm yours."
Klaus resumed rubbing his hard-on into Caroline's clit, and she started her panting again.
"Say 'I belong to Klaus Mikaelson, I am his love.'"
"I belong to Klaus Mikaelson, I am his love," Caroline repeated, then screamed when Klaus inserted himself into her.
Klaus pounded into Caroline, and she exerted small screams of pleasure.
"Don't stop!"
The hybrid pumped into her for, hearing the headboard creak from the pressure. Finally, feeling all her muscles clench in an orgasm, and he released for a second time.
Klaus rolled onto the spot beside Caroline, the mattress still rocking slightly.
"I meant it," Caroline said softly.
"I know," Klaus said, cuddling her to him and stroking her hair.
Caroline was wrapped his Klaus's arms, and his face was buried in her sunny hair as they drifted off to sleep.