A/N: This was the other fic I wrote for the Klaroline Winter Wonderland exchange. AU/AH but set in the future. Technically a fusion, but you do not need any understanding of Overwatch to read. At all.

The beautiful cover was made by purestheartslove, and this fic was beta'd by garglyswoof. I hope you enjoy!

Present

It had taken years for her to track him down.

Caroline watched as he held out a hand over the dead woman at his feet, an orb of twisting smoke floating from her chest and into his hand. She flinched as he crushed it in his palm, making a soft sound of contentment before he turned to look at her.

He looked like he hadn't aged a day, though she was struck by how much paler his face was, the deep blue of his eyes much more prominent against his skin. The only sound in the winter air was the gears in her Valkyrie suit clicking as she let the mechanical wings withdraw, and she stiffened at the way he looked at her, the mix of fear and anger swirling in his gaze speaking volumes. She took a hesitant step towards him. He remained still as she approached, watching her with a calculating gaze. "You look like you've seen a ghost, sweetheart."

Ten years ago...

"It's nice to have you on the team, Doctor Forbes."

Commander Salvatore was tall with a strong jaw and kind eyes, and Caroline gave him a small smile as she shook his hand. "Thank you," she said softly, still taking in the room around her.

She'd been confused when Representative Saltzman had contacted her to join Overwatch, an international military partnership that fought to protect human life from the Omnic Crisis. She was regarded as a scientific genius by most in her field, having earned her medical degree by the age of twenty, but even after three years of post-grad field work she still often felt like she didn't quite belong, that no matter how much her knowledge and willingness to learn was lauded the other scientists still thought of her as a child.

Initially she'd been hesitant when the job was offered to her, wondering if she'd end up doing the same thing but in secret, but once Representative Saltzman had told her that she'd be doing her own medical research, promising her access to the latest technology and an enormous budget in exchange for working part-time consulting at the hospital and the occasional venture as a field medic, she eagerly agreed. It was her chance to do research without being condescended to by well-meaning scientists in lab coats that had 'daughters just her age'.

Now that she'd been flown to the main Overwatch base in Switzerland to begin her work, she'd been introduced to about seven different people, and was having difficulty keeping all the names straight. "Only one more for you to meet," Representative Saltzman said, checking his watch, and Commander Salvatore laughed.

"Klaus, you mean?" he asked. "He's on a mission with a few of the troops, actually. We don't expect him back for another few hours."

"We made good time," a smooth, accented voice said from behind her. Caroline flinched in surprise, turning to face the speaker. He was pulling what seemed like an endless amount of small weapons from various pockets, dumping them all in a pile on the table by the door before standing and running a hand through his hair. Every movement he made, from the flex of his fingers when he set down a knife to the easy way he shifted his weight screamed that he was much more dangerous than the pretty package might lead her to believe.

She shifted as his sights landed on her, bright blue eyes raking up and down her form before a small smile curled on his lips.

"I'm Doctor Caroline Forbes," she introduced when he made no move to speak to her.

"Klaus Mikaelson. Director of Covert Operations and in no need of your assistance. Salvatore, mate, I need you for a briefing."

"You might want to be a little nicer, considering that I'm running the hospital and someday you might get injured and 'need my assistance'," Caroline said, resisting the urge to add air quotes.

Klaus raised his eyebrows, tilting his head to the side, and she could tell that she'd surprised him somehow, that he was intrigued. "Is that a threat, love?"

"Not at all, but triage can be hard, especially in stressful situations," she said, giving him a saccharine smile. "And I prefer Doctor Forbes."

The energy crackled between them as they stared at each other, and eventually Klaus gave her an amused, dimpled smile before turning to look at Commander Salvatore. "My office in a quarter hour. It's urgent."

Commander Salvatore nodded, waiting until Klaus had shut the door before turning back to Caroline. "Don't be offended. He's like that with everyone," he said, and Caroline shrugged.

"I don't care. It doesn't make it okay."

The commander looked like he was torn between horror and amusement before seeming to let it go, nodding once. "I'll leave you to it. Ric can show you where the research center is. The hospital is in the same building. We can order everything you need if you can make us a list."

"Thank you Commander."

"You can call me Stefan."

"Okay."

Director Saltzman led her to the research center as promised, and she huffed when she walked in, finding that the hospital was outfitted with only the basics and the research center with even less. Sighing, she found some paper and a pen and began the long process of making lists of supplies they needed.

She was distracted though; for some reason, no matter how much she tried to concentrate on taking inventory she couldn't stop her mind wandering back to the covert operations director. He'd been more than a little irritating, and based on that first impression she wasn't exactly looking forward to seeing him around the base, but something about the way he looked at her made her skin prickle, though she wasn't sure whether it was because she was nervous or intrigued. Maybe both?

XXX

Caroline shifted as the metal of her newest creation twisted around her skin, fitting snugly but not too tight. She experimentally raised her arm, smiling in satisfaction when she felt a warm charge under her skin. "What are you doing, love?"

She flinched, whirling around, and saw Klaus behind her, his hands clasped behind his back as he observed her reaction, his head slightly tilted.

She managed to gather herself quickly. "Finishing my latest project."

"What is it?"

"I call it the Valkyrie suit," she said, rolling her shoulders in the movement the suit would detect as the activation for her wings to extend. Klaus watched as they unfurled, the metal smoothly extending. "Being able to fly will help me heal soldiers more efficiently in the field."

"In the field?"

"Yeah. For the last few months Stefan has been asking me to come on some of the riskier missions just in case, and I'm happy to help. I was just trying to design something to make me a little safer in combat."

He watched as she bent to pick up her newly-designed staff from the table, and she had the sneaking suspicion that he was staring at her ass. When she turned around to look however, he was determinedly focused on the wall. "Are you sure you're suited for that, love? It's a bit dangerous."

She stared at him, trying to work out whether she'd rather call him out on his misogyny, condescension, or use of an endearment to refer to a colleague, but before she could get her biting retort out, he'd already moved on to looking at the plans on the table. "Does this even have a holster for a weapon?"

"No. I don't need one."

"I won't allow you on my team if you don't have a weapon to defend yourself with."

"Tough. Stefan wants me on the team, so—"

"You'll find that Stefan doesn't have the sway in the Blackwatch that you seem to believe he does."

She pursed her lips, unmoved. "I don't believe in war or hurting people. When I came here I was very clear with Representative Saltzman about that, and he said I'd only be going with you in case people got injured. No murder required."

"He lied," Klaus said with a shrug, stuffing his hands in his pockets. "I'll get you a gun."

"I don't want a gun."

"Tough," he said with a wink, and she gritted her teeth, turning away. He was infuriating, always seeming to bring out the most stubborn and exasperated pieces of her while remaining interesting enough to banter with that she could never quite manage to bring herself to push him away.

In the past few months, she'd found that he was almost fun to be around when he wasn't being an arrogant ass. When she was tempted to go out of her way to spend time with him, she kept having to remind herself of the countless warnings other people at the base had given her when they saw how Klaus acted around her. According to everyone else, Klaus was concealing his selfish, bad-tempered personality in order to get his playboy claws in her pants.

Well, that description was actually Bonnie's words verbatim, but the rest of the base seemed to share her opinion.

"You can bring it, but I won't use it," she said firmly.

"You'll have to at least know how to fire one. I'll teach you, if you'd like."

A solid 'no' was on the tip of her tongue before she swallowed it back, inwardly smirking, deciding to nip these useless 'learning to use weapons'-shenanigans-slash-obvious come-ons in the bud. "Fine, but you have to leave me alone once I get the hang of it."

He was grinning, his dimples cutting into his cheeks, and she found herself wondering whether everyone else could be wrong and that he may actually like her. Her heart skipped a beat, and she felt a bit off-balance, suddenly not quite sure of whether she'd be opposed if he did.

She gave herself a mental shake, telling Klaus she'd meet him at the shooting range in an hour and to get out. He gave her another infuriating smirk and she turned back to the lab table.

She threw herself into testing her new creation until she had to leave. She flexed her fingers as she walked to the practice range, not looking forward to the familiar feeling of a gun recoiling in her hand, and resolved to get the whole thing over with as quickly as possible.

"Caroline, love," he greeted as she approached, and she fought down a laugh at the tiny blaster he held out to her.

To be fair, she had given him the impression that she'd never shot a gun in her life, and it was definitely the kind of weapon she would give to a beginner. At least he seemed to genuinely be trying to help. "It's quite small, but I thought you'd like to get used to it."

"Thanks," she said, reaching out to take the blaster.

"So, first thing you should know," he began as she weighed the weapon in her hand. "Is to always treat the gun as though it's—"

In one fluid movement, she planted her feet and raised the weapon, firing a shot between the eyes of the mannequin on the other side of the range.

"—loaded," he finished dryly. "I see you've misled me."

"I didn't mislead. You assumed," she said, trying not to sound too smug. "I'd like a Caduceus Blaster 3X-T please, preferably in blue, but white is fine. Gotta run, but thanks for the lesson."

She almost expected him to be angry, but instead he seemed amused, perhaps even a bit impressed. "I'll see you tomorrow then, Caroline," he said.

The way her name rolled off of his tongue made her shiver, and she tried not to ruin her dramatic exit with a blush as she turned to leave.

"Your call sign is Mercy," he added. "I'll have someone bring you a communicator."

She turned around, an eyebrow raised. "Mercy? Seriously? Who chose that?"

"Someone who clearly doesn't know you very well," he said dryly, and she grinned, turning to walk away.

XXX

"It's okay. You're fine. I'm here. You're doing great," Caroline said softly as she pulled the last bullet out of the thigh of one of their agents, who was sprawled on the concrete. "I just need to wrap you up now, okay?"

"Thanks," he said gruffly, and Caroline gave him an encouraging smile as she went through her medical kit to find the medicated bandages.

"How is he, love?"

"He's fine," she said without looking up, carefully wrapping the cloth around the man's leg. She was determined not to interact with him too much, knowing that she was growing too attached. Since she'd begun going on missions with him, she'd realized that not only had her instincts been correct about Klaus being dangerous, she also might have underestimated him, just a little.

She'd often seen him kill without batting an eyelash, looking away disinterestedly as the corpse fell to the ground. The first time she'd witnessed it, the man he murdered had been advancing on her as she cared for a fallen agent. She'd felt the world press around her when she heard the gunshot and the splat of bullet meeting flesh, the scream ripped from the man's throat making her shiver. It was her town being torn apart by the war all over again, and she gritted her teeth as she tried to center herself. Klaus had nudged the man's body to the side with his boot to approach her more easily and calmly bent to sit beside her, his hand pressing soothingly against the small of her back until she calmed and was able to return to her patient.

It wasn't until she'd arrived back at her small apartment later that night when she realized that even after watching him murder a man like it was nothing, she had still trusted him to comfort her, and it scared her.

He was still looming over her now as she finished binding the agent's wound, and she huffed, looking up at him. "What?" she asked irritably before she registered what she was looking at. "Oh my god! What happened to you?"

"It's not mine," he said simply, wiping some blood off of his nose with the equally bloody back of his hand, and she felt nausea swirl in her gut.

"That's so much blood," she breathed.

"Never thought you'd be squeamish, Doctor Forbes."

"I'm not," she snapped, unable to stop staring at the way his clothes were practically soaked with it, the red liquid smeared across most of the skin that was showing. "I'm just...how?"

"Do you really want to know?" he asked warily, and she immediately shook her head.

"No. Don't tell me."

"All right."

They were both still as Caroline continued to stare, trying to push down her curiosity, and the silence was abruptly broken by the soldier. "Um, can I go now?"

Caroline shook herself, running a hand through her hair. "Oh! Yeah. Sure. You're all set."

The soldier pushed off the ground, the wonders of technology having done their job so well that he wasn't even favoring his uninjured leg.

She watched him go before turning back to Klaus, wincing again at the amount of blood. "How many?" she asked, unable to stifle her curiosity.

"Four," he drawled, his lips twitching.

"How can you be so casual about killing people?"

"How can you be so casual about wanting to leave those murderers alive?"

"If you kill them, you're also a murderer," she said quietly. "You just have a faster draw."

"It's necessary for what we're doing."

"I'd buy that for some, but not for this many. If you didn't prolong their suffering there's no way you could have ended up covered in this much blood."

"Perhaps I enjoy it."

"That's disgusting," she said with a curl of her lip.

"Are you going to check on my soldiers or continue scolding me for things already over with?"

She gritted her teeth, standing. "Have we almost finished the mission? It might be easier to take the injured to the hospital, depending on severity."

He nodded, holding out a hand to help her stand, and she took it without thinking, leaning down to pick up her medical kit once she was up.

"That looks heavy."

She shrugged. "It's not that bad."

"I can carry it if you'd like."

"So that you can smear the blood of people you killed all over it? No thanks."

He glanced pointedly down at her hand that wasn't holding the medical kit, the one she'd given him to help her up, and she followed his gaze. Shining red blood was streaked across her palm, and she swallowed. "You didn't stop me," Klaus said quietly, the double-meaning of his words heavy in the air, and she looked up from the evidence of his kills smeared on her skin to see him looking at her, his head slightly cocked to the side.

She knew she had a part in it, standing by and healing the people who killed, but Overwatch's goal was peace, and she could convince herself that as long as the deaths were not needless, the ends justified the means.

Still, there was blood on her hands.

"Just try to keep it to a minimum," she said, holding his gaze, and a small smirk twisted his face.

"For you, sweetheart? I'll try to resist the urge to torture before I put them out of their misery."

"How do you not feel guilt for this?"

"I'm a high-functioning psychopath. Haven't you heard?"

"Multiple times, but I don't believe it."

"Perhaps you should."

"I think that you care, even if you try not to," she said quietly, rolling her shoulders as though she could shake off the memory of what she'd done. "You feel every kill weigh on you, deep deep down, but having someone's life in your hands makes you feel so powerful that you can't shake the rush it gives you. Every time you feel the guilt, you just take another hit to remind yourself that you're more powerful than the ghosts of your actions."

His face was unreadable, though his body was stiff, and she knew she'd hit the nail on the head.

"How?" he asked quietly, and she nervously tucked a lock of hair behind her ear, flashes of the bleeding corpses of her family's murderers still burned into her mind like a brand, the memory of how much she'd liked watching them suffer still making her stomach twist with nausea.

"You were right," she said quietly. "Whoever gave me my call sign didn't know me at all."

He raised an eyebrow, but she walked away from him, her knuckles white around the handle of her medical kit. She tried not to think about how well she understood him, how the temptation had nearly overtaken her more than once. Despite her best efforts, she was falling for Klaus, and she knew it. He offered her something that she doubted anyone else ever would: understanding.

He saw her faults, even before her confession just minutes before, and it was nice to have someone not put her on a pedestal. It was nice to not have to face the disgust she knew would be present in anyone else's eyes, because she was already weighed down with guilt without the help of anyone else's scorn.

She knew she should be concerned that she was tempted to fall into the arms of a monster like him. Still, she knew he'd never blame her for the darkest parts of herself, and that would be...freeing.

She swallowed, pulling herself back to the present. She had people to save, even if it would never absolve her guilt.

XXX

"Klaus, you're being ridiculous," Caroline muttered.

"You nearly died."

"Do you know how many times you've nearly died on a mission since I started going?"

"No, because unlike you, I had a perfectly functioning support agent to patch me up. You have no one to take care of you if you go down."

"I have you, and I think you did fine. It was a bit closer than usual, but he's definitely very dead," she said lightly.

"And if I hadn't been there, what would have happened?"

"It's your team, Klaus. You're always there."

"You're missing the point, love—"

"I think I'm getting the point just fine, thanks," Caroline said, taking a sip of her coffee and trying to resist the urge to excuse herself to get more poundcake from the bakery counter. "You're concerned because there was nearly an accident on the mission. However, not only did you intervene when it happened, but there is almost no chance it would have been fatal. I appreciate your concern, but you're not going to stop me from doing my job."

"If I recall correctly, your job is a researcher, not a field medic."

"It's still a part of my job," she said calmly. "Yes, my research takes priority, but it's important to contribute if I have free time."

He pressed his lips together, clearly considering something, and she braced herself for another round of debate before he spoke, making it clear that there was no need. "Fine."

"Fine?!" she repeated incredulously.

"What, do you want me to disagree?"

"No," she said immediately, ignoring the tiny part of her that kind of wished he'd fought a bit harder. "It's not your choice anyway."

"That's true," he said, taking another sip of his tea before changing the subject. She couldn't focus, every instinct she had blaring that this argument was far from over and that he was biding his time.

Klaus's angle became clear the next day when Tyler, one of his subordinates, arrived with a binder that he explained was a research proposal. She took it, telling him she'd get back to Klaus later that day, and opened the binder to fifty pages proposing a long-term project to create about three hundred "upgrades" for the field.

"Seriously!?" she hissed to the empty room as she came upon the phrase "self-wrapping bandages" on page two, and by the time she got to "socks with adjustable thickness for harshly cold climates" on page seven, she was fuming.

Her fury built steadily as she read through the paper, and by the time she got through the first ten pages she was frustrated enough with the bogus research backing up the suggestions that she uncapped a red pen to circle the false medical facts and correct them, starting most of her responses with "WELL, ACTUALLY..."

In all caps.

She was not pleased.

By the time she arrived at Klaus's office door two hours later, she wasn't sure it would be possible to be any angrier, but when she saw the shit-eating grin on his face, she knew she'd been wrong. "What. Is. This?"

"A detailed proposal advocating for necessary upgrades to the medical facilities to better support our troops. It says so in the 'objective' portion on the first page. Have you read it?"

"Thoroughly," she growled, dropping it on his desk with a thump. "And I will be researching exactly none of these."

"It's been approved already, sweetheart."

"Who did you bribe?" she snapped, making a mental note to make whatever board member it was's life miserable until the end of time.

"Classified," he said with a grin.

"Well, get whoever it is to un-approve it."

"Afraid not. These changes are necessary, you see."

"They are not," she bit out. "You are trying to keep me in the lab so that I'm not in the field, and it's wrong. I have literally never felt so disrespected in my life, and I did my internship at a practice with three people twice my age who all tried to get me to date their sons."

"Caroline-"

"Don't. This is shitty and horrible and wrong on so many levels, and, in case you can't tell, I'm furious."

"I did get an inkling of that, yes."

"What is your problem?" she demanded. "Why do you want to keep me out of the field? You don't bat an eyelash any time Stefan or Marcel go, and I'm just as good a shot, if not better."

He seemed to not know what to say, and she smirked, knowing that her argument was logically sound. She expected him to make another bullshit excuse or lash out so that he wouldn't have to admit that he was worried, but she was taken aback when he didn't. He folded his hands together and gave her a look that indicated that whatever he was about to say, he was not joking. "I care about you," he said softly, simply.

The words shouldn't have surprised her. He showed her that he cared constantly with little gestures or favors, but there was something about Klaus outright admitting it that caught her off-guard. "Yeah, but you care about Marcel and Stefan too," she said, trying to keep her voice confident. "We're your friends."

"Don't pretend that you don't know that I've fancied you since the day we met, Caroline."

"Of course I know," she said before she thought about it. "But that's not the point."

He flinched at her blatant dismissal of his confession, but she couldn't find it in herself to feel bad. "Isn't it?"

"No! If you know me at all you know that I'd never let anyone trap me like this."

"Of course I know."

"Then why do it?" she demanded. "It's not like you thought I'd just let you keep me locked up in my lab without a fight."

"Not at all. Have mercy on a man who dared to hope that you'd make the choice to stay safe."

"This is not the time for callsign puns," she snapped.

"Ah, yes. My apologies. We'll return to me admitting my feelings for you while you brush them aside, shall we?"

"First of all, I don't owe you emotional cushion for admitting your good taste, and it's not like you didn't know I like you. I appreciate you giving me the time to admit it to myself or whatever, but the point of this conversation is that you're trying to prevent me from going on missions to save lives, which, in case it somehow slipped your mind, is literally my job."

He let out a sharp breath, leaning back in his chair and steepling his fingers. "Fair enough," he said softly.

She watched him as he seemed to make a decision before standing abruptly and walking around the desk to stand uncomfortably close to her. She met his eyes, her lips parted slightly, her breath catching. "What are you doing?"

"Can I bargain for only significant missions?" he asked as he stopped in front of her, his gaze serious and hard. "I trust you to take care of yourself, Caroline, but I'd also like you not to have to."

She tried to figure out what had changed in the air, when his gaze had turned from angry to concerned. It was an odd feeling, that whiplash of his emotions, the certainty of his affection for her. She leaned closer without thinking about it, knowing that she was probably giving in too easily, though she didn't resist when he cupped her cheek, leaning into his touch. "Fine. Just significant missions, as long as you aren't an ass about which ones count. It's the honor system, okay? This is my choice."

He nodded once, and she held his gaze as she felt anticipation build within her, the crackle of energy prickling under her skin as her mind raced, wondering if they were about to take the plunge, to really commit to what they'd been dancing around for the past year. She was answered when she leaned forward just enough to give him the hint and he bent to press his lips to hers.

It was better than she'd imagined, his lips moving perfectly against hers in a way that made her toes curl, his tongue slipping between her lips to run along the back of her teeth, curling against the roof of her mouth. She arched her back as his fingers nimbly undid the buttons of her lab coat, helping her shrug it off, her nipples stiff and sensitive against the fabric of her bra. His hands seemed to be everywhere at once, branding the skin of her shoulders and thighs with the tips of his fingers, his touch making her limbs feel like jelly. She threaded his necklaces between her fingers, tugging them and savoring the low groan in his throat as he ground his rapidly hardening cock against her thigh through the rough fabric of his jeans.

Her cheeks were hot, the tension and crackle of energy that she expected to melt away when she gave in only swelling as she felt her body respond to his touch. She already ached for friction between her legs, and she moaned as he slid a hand under the skirt of her sundress, running the tip of his finger over the waistband of her thong.

She moaned as he tugged the lace to rub against her pussy, feeling breathless and desperate, and tipped her head to the side so that he could nip the sensitive skin of her shoulder. A shiver ran down her spine at the feel of his tongue and teeth against her skin as his fingers teased her through the lace barrier that she ached for him to remove.

That was when she caught sight of the clock on his wall.

"Klaus," she breathed, her head tipping back against the wall as he nipped her neck. "I have work to do."

She expected him to try to convince her to stay, to give her an excuse to slump against the wall and let him touch her until she felt heavy and sated, but instead she felt him smile against her skin before he pulled back. His eyes were dark with lust, his lips slightly swollen, and he pressed a soft kiss to her lips. "Fine, then. Have a lovely afternoon toiling away. If you change your mind, however, I'd love to see if you look as lovely bent over my desk with your knickers stretched between your legs in reality as you do in my fantasies."

She flushed, narrowing her eyes. She saw what he was doing, making it so that she had to admit how much she wanted him. If she walked away, she'd be hot and bothered all afternoon, but unable to come back to him without seeing that stupid smug smirk. She was wet and empty and seriously tempted to give in, but she shook her head, letting her tongue skate over her swollen lips. "Well, I'd like to see whether you look as good on your knees for me with your face between my thighs as you do in my fantasies, but I guess we can't always get what we want."

"You fantasize about me?" he asked, a smirk spreading across his face. "What other dirty secret desires do you hold in that lovely mind of yours?"

"Ones that you won't know until I'm not as busy. Unfortunately, someone bribed an Overwatch board member to make me have to work on all of these very important upgrades, and if I have to do all of them, I think I'm going to be too busy to spend time doing anything for the next year. If only someone could fix that..."

He grinned, bending to kiss her again, tugging her lower lip between his teeth, the sting making her pussy clench. "I'll see what I can do," he said as he pulled back, her breath catching.

"Also, don't think I didn't see what you did there," she said, her hands skating up his chest to tangle his necklaces between her fingers. "Making staying home from less important missions seem more reasonable by sending a completely unrealistic opener was smart, but totally manipulative. Do a little work, and I might forgive you enough to let us both get what we want."

A/N: Thank you so much for reading! Please let me know what you thought :D

I'll be putting up the second part next week. I'm thinking I might do an epilogue as well, but I'm not sure yet. If you'd be interested, let me know!