AU. 4x16 never happened and Klaus is still in Mystic Falls.

Love was a funny thing, wasn't it? No matter how much you built up your walls, pushed people away, love somehow always seemed to find a way to break through your defenses.

He'd asked his brother about it once, when they were human and he could still stand Finn and he wanted nothing to do with Elijah. Before everything changed.

"Why does it hurt so much?"

"So you know it's really love."

For a thousand years he tried to fight off love towards everyone. He pushed down his love for Tatia, buried it under layers and layers of hate and anger, drowned out the memory of her. Found solace in the arms of others. And on particularly bad nights, he killed them when he found himself thinking that maybe, just maybe, he was tired of being alone and pushing everyone away.

He lied to Elijah. Love wasn't a vampire's greatest weakness. Love was his greatest weakness; he craved it and despised it in equal measure. But that wasn't a vampire's greatest weakness. He wasn't sure that he even knew. Was it holding onto their humanity? Giving into their vampiric urges? Or was it being afraid and paranoid? Maybe there was no great weakness for the vampire species.

Klaus' was that he was afraid of being hurt.

So he wrapped himself it tight, put on armor and built up walls upon walls upon walls upon walls.

No one would hurt him ever again, no one would have that power over him.

And then she brought all his walls down with a glance.

He didn't notice at first- he would find it odd later that he hadn't noticed; he'd relied on them for so long to keep him safe- but he found himself doing things that he'd thought he'd long since put behind him.

He couldn't kill her and eliminate her-it sounded far worse when he took the time to think about it-, couldn't put her in a box like he could his siblings when they did something idiotic and put their lives in danger.

Like fall in love, for instance.

Someone should definitely dagger him; he was turning into a pathetic sap. Hell, he was as bad as Elijah.

And then she would smile at him again, and he didn't care.

But she wasn't his. Couldn't be his? She wasn't even Tyler's, he could see that much, and perhaps that was what kept him from ripping the fool's head from his shoulders. She belonged to herself- she was free and freedom and he wanted to simultaneously watch her discover herself and catch her for himself.

If you caged a thing- a person- you loved, would they want to stay with you if you let them free?

And he would have to let her free, that much was certain. He wouldn't keep her caged, if he gave into his darker urgings, the urgings that said to claim her and take her and never let her go no matter what lengths he had to take… but he couldn't do that. He loved that she was free and stubborn and truthful and caring.

He thought that maybe he loved her smile most of all.

Did it matter if her smile wasn't always for him?

It did. It hurt to see her smile at anyone else. She smiled at everyone; her friends certainly, that damned hybrid that he should have killed when he had the chance, babies and old people, dogs. Did that make him less special?

(He refused to acknowledge that following her was creepy. Concerned? Yes. Protecting? Definitely. But not creepy. And she saw him, he knew that she did, even if she never acknowledged it.)

It didn't. If she was smiling she was happy. Alive. And that made some of the pain go away. Especially when she saw him again, and the smile would gradually light up her face, and he swore it was better than being able to be in the sun without his daylight ring for the first time in centuries. Warmer. Happier.

Being with her made him happy. Seeing her happy made him happy.

He asked Stefan about it- they were in the phase of their friendship where Stefan was alright with being with him if he was drunk, and he didn't care as long as he could have his friend back for a night at a time.

"How can I be in pain but happy at the same time?"

"That's love, Klaus. Knowing the other person is happy is more important than your happiness."

So he let the damned boy- thrice damned! he shouted one alcohol-fueled night- back when her smile grew too dim and the warmth slipped farther and farther away and nothing he did could bring it back except to do the one thing that caused him the most pain.

All his excuses revenge and anger were false. Well, they were true, just not as true as he led everyone to believe.

The worst part of loving someone was wondering if they were in love with someone else. And he knew. He had to watch it. Saw how her face lit up, how the smile never seemed to leave her face, just growing more and more luminous and dammit why couldn't that be for him?

He wanted to kill Tyler.

He wanted to kill her.

He wanted to see her smile forever.

Was it fair that he only wanted it for him?

Of course not, but he was a selfish being. His nature. If he didn't keep a tight reign on things-people- they left him or were taken from him. But if he held on too tight they grew angry and bitter and hated him.

And then when would he see her smile?

He grew to hate and love her smiles in equal measure.

Caroline's happiness was Tyler's happiness.

Klaus' misery.

The pain spread through his chest and infiltrated his brain, filling it in his waking and sleeping hours with visions of what she was doing with the boy that made her so happy.

He was so caught up in his own misery that he didn't see how her smile didn't light up her face anymore. The smile never reached her eyes.

He couldn't see that the smiles she gave her friends, and the thrice damned boy, the babies and old people, and the dogs she saw on the street were becoming more and more forced.

He only saw when she smiled at him because when he watched her smile at other people the pain grew more and more and more and it threatened to overwhelm him… he couldn't watch that anymore.

And when she smiled at him, the smile started in her eyes and- if it were possible- her face grew more beautiful and more light as the smile stretched across her lips.

For him.

And that made joy spread in the same area that he was so used to feeling pain in. His chest? His heart? (If he had one, he could imagine her joking) His soul?

It became worth the pain for those brief moments of joy- joy, a feeling that he wasn't used to. Wasn't it amazing that this girl, who he might not have met had things gone different- he shuddered at the thought-, this girl who seemed so inconsequential in the great scheme of things was the one person who could make him something that he couldn't even remember being as a human?

Did she know, would she ever really know, or understand what she did to him? How she changed him?

He didn't think she would. Didn't think he would ever build up the courage to tell her.

But surely she could see, couldn't she?

Was he deluding himself, thinking that she couldn't see him as much as he could see her when all she'd ever done was see past his defenses?

"Klaus? Klaus!"

Shrill- that was how Rebekah described her voice.

Loud and invasive- that was Elijah's description.

He'd rolled his eyes at both of them and their descriptors. They were wrong, so wrong. Melodic, maybe. And it made him feel needed. Wanted.

"Caroline." And he tried to keep the smile off his face upon seeing her there, but her smile, already in place and waiting for him as it almost never was, destroyed his plans. "What can I do for you love?"

Her smile grew wider, and yet more apprehensive at the same time. "WelltheresapartytonightandIwashopingyoudgowithme? "

He couldn't help it, he burst out laughing and almost continued when he saw her lips twist in a scowl. But he wanted her smile back, so he fought off his chuckles- were his eyes playing tricks? or was he really seeing the corners of her lips begin to twitch up in a smile? "What was that?"

She sighed, but her smile returned. "There's a party tonight and I was hoping-wondering- if you'd like to go with me?"

Confusion and happiness flooded him in nearly equal measure. "But I thought Ty-"

The smile slipped from her face again-he wondered if he'd be so fixated on making her smile if he could kiss those precious lips. "Klaus I swear, if you say that name I'm leaving right now."

He was unused to the venom in her voice, so he nodded quickly, more than willing to drop the matter of Tyler. He told himself he didn't care. He didn't care if she was just mad at the boy or if they'd actually broken up. She was here, and she wanted him to be with her.

That night- that party- turned into another and another, until by unspoken agreement they turned up at everything together.

She'd kissed him one night. Tyler had come in with some girl.

Klaus didn't speak to her for two weeks.

Then she turned up, tears in her eyes and apologies on her tongue, and he put it behind him.

Kissed her for real. It was heaven to feel her lips curl into a smile under his.

He could see what he'd been missing. How her smile wasn't as bright for everyone else. She seemed to be fighting with everyone-but Stefan and her mom and him- and he couldn't figure out why….

Until he saw Elena glaring at them from across the bar.

"Caroline," he was concerned now because if he robbed her of everyone she loved would she be happy forever? "Are your friends alright with...us?"

She sighed and rolled her eyes and crossed and then uncrossed her arms, grabbed his hand from across their table. "Klaus, you know… you know how they feel about you. It's not… fair. Or right! It's hypocritical really, given Damon's track record. I don't care though, I- I like you. I want to be here with you." She paused, looking down at their entwined hands. "You make me happy."

He found that he wanted nothing more than for her to say those words to him always.