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by fate's design

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There were few people in Mondstadt that Jean had as much trouble talking to as she did Diluc. Maybe it was just his subtle tendency as an Alpha to be a bit intimidating, but… well, all else aside, she was a Beta, and really, it shouldn’t be this hard. In all likelihood, it was probably the anticipation of the expression she knew he was going to make when he realized she was standing in the Angel’s Share not to buy a drink, but to discuss Kaeya.

“...Have you seen the Cavalry Captain?” She asked, before anything else, because unlike Kaeya she did not like to wheedle her way in on false pretenses. Diluc’s neutral expression dropped into something darker, his frown deepening. Still, he respected Jean, so the answer was not as harsh as it could have been.

“Am I his keeper?”

Biting her tongue, Jean did her best not to wince. “No, no you are not, I just—we have not seen him, for a few days, and he’s on the register for sick leave. He hasn’t answered the door to his apartment when I’ve knocked for two days.”

“Kaeya doesn’t take sick leave.” Diluc can’t really help the fact that the words tumble out of his mouth before she can finish, and Jean gives him a sheepish, but… knowing look.

“He doesn’t. That’s why I was asking if you’d seen him,” Jean countered, and as loathe as he was to admit that he was the one who would be able to likely find him the easiest, he knew why she was really there. She didn’t like to call in favors, but…

“I’ll get Charles to take over, and go check,” he agreed quietly, and the tension bled from her shoulders.

“Thank you, sir.”

“Diluc,” he corrected, but she was already on her way out. Life was a constant state of business for the Acting Grand Master, after all.

He was a little more concerned than what he let on, though. Even when Kaeya had been running fevers and feeling miserable as his right hand when Diluc had still worked in the Order, he hadn’t taken sick days unless Diluc physically forced him. Perhaps it was some desire to prove himself even after it became a little more obvious he would one day present as an Omega, that he could handle any challenge. Though Kaeya had presented after Diluc had left, he could only assume he kept that strange sort of ethic. Idiot.

Though Charles enjoyed the less strenuous days where Diluc picked up a shift as well, he seemed to understand completely when Diluc mentioned needing to take off early; Diluc couldn’t help but wonder if Charles had come to the same conclusion as the rest of his staff had at one point, that he was the Darknight Hero, or… if he’d overheard his conversation with Jean. Possibly both.

While Kaeya hadn’t answered his apartment door for Jean, Diluc didn’t let little things like doors stop him. With his mask up, just in case someone did catch him breaking and entering, he made his way around to the ledge of the building, intent on testing the window.

It was pulled open just a bit, leaving about an inch of leeway between the frame and the window itself, but that… was more suspicious to Diluc than anything else. Kaeya knew better. If he wasn’t in, he wouldn’t have left his window open, and he could see the shape of a body under the blankets of the bed.

“Idiot,” he announced gruffly as he pushed up the window to slip in. “If you’re just sick, you could have at least answered the door for Jean instead of worr-”

He stopped dead in his tracks as his feet hit the floor, and he understood very quickly why the window had been cracked, and likely why Kaeya hadn’t opened the door, either. The sweet scent of an Omega in heat stirred immediately at the pit of his stomach, but there was something… different about it, too.

Many times, Diluc had heard the other knights speculating on why their Cavalry Captain hid his scent. There were rumors of it—though everyone knew that he was an Omega, they ranged from the thought that maybe he had an unpleasant scent (doubtful) to maybe he was trying to hide from what legends liked to boast as a ‘Fated Pair.’ Diluc had scoffed often about the notion, thinking that it was just as ridiculous as simply being fond of the scent of ones mate that they’d boast it as woven into fate itself.

The pleasant scent of what had to be mist flowers blooming on the edge of a sea of calla lilies hit his nose, and Diluc’s knees went weak enough that he had to reach out and grasp the window frame again.

It wasn’t the normal ‘protect, tend to, take’ that Alpha instincts shouted in the middle of a rut. No, this was not a rut-response to an unmated Omega’s scent, this was…

Guilt that he hadn’t noticed it sooner. Torment that Kaeya had been suffering in silence. Shame that he had never realized that Kaeya was hiding his scent because he must have known all along that they were Fated. Diluc felt sick that he had been too stubborn to notice, and the realization of how much it must have ached to even be in the Angel’s Share with him when Diluc did nothing to restrain his own.

Before he could resent himself any more for it, Kaeya’s shifted, the noise and Diluc’s voice dragging him out the haze of sleep that he’d slipped into to avoid the discomfort of his heat. A certain discomfort worked its way over his features as he realized just who it was that had broken into his apartment, though, and he exhaled sharply.

“Diluc,” he murmured, voice quietly apologetic, but Diluc couldn’t tell if it was over the fact that he could tell that Diluc now realized judging from the look on his face, or the fact that he’d apparently caused so much concern that Diluc had had to break in.

He should have scolded him. He should have admonished him for not letting anyone know about this, he should have been angry that Kaeya hadn’t been honest.

But really, could he blame Kaeya for hiding it?

In a thousand lifetimes, Diluc wouldn’t have been able to find a way for both of them to make amends without either of them still feeling somehow at fault. Not if this hadn’t happened, at least. In silence, he stepped forward, taking in more of the sweet scent that drew out his own in response, as shameless as it was. He could see the unease in Kaeya’s expression, thinking that Diluc was judging him, furious or dejected over this revelation. The knowledge that Kaeya had tucked away so much of himself to avoid being honest with Diluc was just another lie, wasn’t it?

He almost flinched when Diluc reached down for the blankets, and Diluc hated knowing the division between them had caused that reaction—that Kaeya may not have feared him, but that he didn’t know if he could trust him in return, anymore.

Something inside of him screamed at that notion, that he had been a horrible Alpha. He could agree.

He didn’t plan on leaving it like that. Not when Kaeya needed him.

“Easy,” he whispered slowly, sinking into the mattress next to him, reaching out to brush the hair from Kaeya’s face. He was feverish, as Diluc knew heats could cause, but more so than that, he looked miserable in a way someone could only be when sitting in three years of unrequited love and averted destiny. It’s enough to make Diluc’s heart twang with that guilt again. “You weren’t going to tell me?”

His fingers brush down the flushed, dark cheek, and Kaeya’s gaze closed, letting out a short, harsh laugh. “It wouldn’t have made a difference.

“That’s not true-” Diluc started, wanting to defend himself, even though he wasn’t sure he had a right to, anymore. “I...”

“Hate me?”

Maybe he had, for a few precious days, or weeks, or months before Diluc had tossed himself too far into avenging his father to hate anyone but the group responsible for his death. “No. Not you. I was angry, but… this is different.”

Kaeya didn’t dare let hope cross his expression, but his eye does open again, inquisitive and confused.

Diluc dipped down, and pressed a slow, careful kiss to his lips. Immediately, warmth blooms in his chest, the first satisfactory thing that he had done in… well, a long time. Kaeya couldn’t help but laugh, quiet and miserable.

“This is a heat hallucination, isn’t it?” Kaeya asked, deathly quiet when the kiss broke. Diluc knew it wasn’t quite the moment to laugh in return, but he did, the sound a little nervous and uneven.

“No. This is me being a good Alpha, and taking care of my Om- … you, through your heat, if you’ll let me,” he answered, his fingers reaching down to red on the blankets. Though he could feel the warmth radiating off of Kaeya’s body, he knew that Omegas tended to feel cold without the layers of blankets in the nests they built, and… Kaeya’s nest was neat, sweet and warm and tempting, built well for how little Kaeya seemed to indulge in his Omega tendencies.

If he had been suppressing his scent, Diluc could only wonder how long he’d suppressed his heats, too.

The promise of being taken care of, of having an Alpha to carry him through the days of weakness, discomfort, and pain… Kaeya exhaled softly, but his uncertainty lingered. “...You want me?”

“I’ve wanted you for a very long time,” Diluc admitted, to both Kaeya and himself in that quiet moment. “I’m not that great with words anymore, Kaeya. But I can show you.” It wasn’t hard to notice the fact that he was no longer the sociable Cavalry Captain—and how Diluc’s forced-pleasant words only came when he was hiding something or caught up in business. Only recently had he started to recover from everything that had made him close off from the world.

Slowly, Kaeya shifted over, making room for Diluc in his nest in a way that could only send one message. Diluc felt as if he’d been given something precious, and moved to shrug both his cloak and his shirt off before slid under the blankets with him, because with his own natural head amplified by his Vision, and how Kaeya had been warming the sheets with his body already.

Instinctively, Kaeya curled into his chest the minute Diluc’s body hit the sheets, burying his nose into the crook of Diluc’s shoulder, drawing in his scent like he’d been suffocating and Diluc offered pure air. Kaeya’s own aroma, sweet and cloying with heat, made Diluc shift back just enough that the other wouldn’t feel how hard he was from the moment he’d first caught it by the window.

“I’m happy to help you, but I want to know that it isn’t just because of your heat that you’re agreeing to this,” Diluc started slowly, gently coaxing Kaeya away from wrapping around him just yet. He was...painfully aware that Kaeya had likely gone to bed in just his underwear to deal with how uncomfortable fabric felt on his skin. Diluc knew he could barely tolerate it in a rut, he couldn’t imagine what it was like for an Omega.

The words make Kaeya flinch, and carefully, he lifted his gaze to meet Diluc’s. “I’ve been holding back for this long so you wouldn’t think you were obligated to do this for me. I’m not here to trap you in...”

“A Fated Pair?” Diluc offered, finishing the words that Kaeya seemed to be unable to bring himself to. Of course Kaeya had done it without consideration for himself; how badly, and for how long, had he wanted this? Diluc was foolish to have even suggested it. Instead of waiting for Kaeya’s answer, he instead tilted forward to press a kiss to the other’s jaw. “Roll over. Lay on your side, facing away from me. I’ll take care of you.”

Kaeya looked as if he might want to protest the loss of Diluc facing him, the ability to hide his face in his shoulder, but… his words are a sweet promise, and Kaeya rolled over to face away. Diluc’s hand settled warm over his bare side, roaming against the skin and the passing scars there, plenty of them surely scored while he’d been gone. He settles closer, his hips pressing flush to the curve of Kaeya’s back and bottom, though he focused much of his attention on the curve of his shoulder.

The scent was strongest there, making Diluc’s jaw clench with the ache of how badly he wanted to find the curve of his neck and mark, but he wouldn’t do that just yet—not until Kaeya was through the worst of his heat and could decide whether or not he actually wanted Diluc too or not. That, however, would not stop Diluc from leaving several, less significant claiming marks across his shoulders once Kaeya was enjoying himself a little more.

Just the first graze of his sharper incisors against the pretty curve of Kaeya’s shoulder was enough to make his Omega inhale sharply, while one hand snaked under him to wrap around him, his hand splaying on his stomach. Immediately, whether it was his own, innate desire, or the scent and purpose of the other’s heat, he imagined it growing slowly under his touch, day by day and night by night, and Diluc let out a shuddering breath against the back of his shoulder. He let the touch slip lower, along Kaeya’s navel, until it reached the hem of his underwear. Without bothering to push it down, he instead dipped his fingers under the fabric, stretching it against his wrist.

Much like himself, Kaeya was already hard—but he could only imagine just how long he had been hard, suffering in semi-sleep of his heat. Diluc’s hand wrapped around him, and immediately Kaeya rolled into his touch, exhaling softly as Diluc’s other hand, still steadfast on his side, drew him back against the rise in Diluc’s pants. It served as a solid reminder that Diluc wanted him just as much as Kaeya needed him.

The scent was stronger under the folds of the blanket, and he reached down with his other hand, as well; both tucked under Kaeya’s underwear, but where Diluc’s first hand had wrapped around his cock, his other folded, exploring between his thighs. His fingers found the warm, wet signs of Kaeya’s arousal there, too, and he dragged it upwards between the valley of soft skin to curl against the slick opening there, nestled just under Kaeya’s length. Despite the chill of his body, his core was warm, and Diluc apologetically kissed the back of his shoulder for making him wait this long.

“I don’t have to knot you, if you’re worried. This is last minute, so there’s not really time for me to go prepare any kind of contraceptive-”

“If you get me this worked and don’t knot me, I don’t think I can forgive you,” Kaeya admitted with a short, strained laugh. There was enough humor in it that Diluc didn’t think he had to worry about it being his heat speaking, but he still couldn’t help but let a nervous smile press into the kiss he left against he back of his neck.

“That’s risky.”

“No riskier than leading troops of men or living like a vigilante.”

Diluc almost winced, reminded of his persistent, stubborn Omega and how hard he worked for the knights. “Fair,” he murmured, using it as the last punctuation before he curled his fingers into Kaeya, silencing their conversation by drawing a muffled keen from him that Diluc commits himself to hearing again and again.

Though Kaeya was tight, there was a soft give there, as well—the sort of natural ease that an Omega in heat had to penetration, and Diluc found himself grinding again against him, through too many layers of fabric. Placing another open-mouthed kiss to his shoulder, scraping teeth there in an effort just to feel friction against them, he left Kaeya’s cock untouched for long enough to reach down and push his pants down. To apologize for abandoning him after getting him worked up, he kept the slow pace of fingering him, dragging along his front wall in a way that seemed to make Kaeya squirm against him even more.

Diluc didn’t miss the shiver of delight when he pressed his own cock, knot threatening to start swelling already, against Kaeya’s lower back, rutting against him slowly just for the pressure while he finally started to slide Kaeya’s underwear to his thighs. He made a note to go get the other some water after this—with how wet Kaeya was, surely he was going to dehydrate, or something like that—Diluc had never paid the closest attention to conversations about how to properly care for a partner, but making sure an Omega in heat was well hydrated and fed was practically a basic.

That would have to be after they were no longer tied, though.

When Kaeya’s underwear at least made it down his thighs where it would stay, because Diluc was a little impatient too, the Alpha allowed himself a few lazy thrusts between his legs, before he positioned his cock upwards, lubricating it with the fluid that still clung to his fingers when he pulled them out of the other. But then Kaeya groaned in complaint, empty and untouched, and Diluc wasted no time in rolling up one thrust, burying himself into the Omega on the first thrust. Kaeya’s noise was sweet, satisfied in a way that wanted more but simply pleased that he was getting it at all. Diluc’s hand, now a little less wet, dragged down his top thigh and pulled it upwards, spreading Kaeya easily for him before he started to set a pace.

The Omega half buried his face into his pillow, but that just exposed his neck for Diluc to mark up with a series of little suckles to the skin, while the hand under Kaeya finally settled on his member again, stroking him slowly to match how he moved within him. “So pretty,” he murmured, finding the words spilling from him before he could help it, burying them into the back of Kaeya’s ear. “You’ll make such a pretty mate, Kae. I’m going to fill you up,”

They were sweet, just the sort of praise any Omega flourished in in the heat of the moment, and Kaeya let out a shaking breath. Diluc could swear he felt him squeeze, and the reaction made him push deeper, until he could hear the soft smack of his hips rocking into him. He lifted Kaeya’s leg a little higher, just so he could sink deeper into that welcoming velvet, already feeling the small resistance of his knot trying to swell.

He wouldn’t expect Kaeya to make it long. Omegas were notoriously easy to make cum wrapped up in their instincts, and already the Cavalry Captain was like a left in the wind in his arms, all sweet shivers at the slightest brush of his fingers or kiss to his neck. He’d probably regret vowing to not mark him until he was coherent, but judging from how many love-bites he’d already left, it’d have plenty of skin to satiate that desire.

“Diluc, Diluc please-” Kaeya finally rasped, rocking back into him. “I need you to knot me, I need-”

“Shh,” Diluc coaxed, offering a few, harder thrusts to give him that satisfaction—but that was all that it’d taken to push Kaeya over the edge, cumming against his hand and the sheets. The way he squeezed down, though, was a little less expected, and Diluc’s knot caught immediately in the sudden tightness. The Alpha buried his face into the side of Kaeya’s neck and nipped just a little harder than he intended to, groaning into the skin as he knotted him snugly. He lasted only a few more, deep rolls of his hips, no longer able to pull out before he felt himself throb with the force of his own orgasm, filling Kaeya just as he’d promised.

The rush of heat, without a single drop able to escape from how well Diluc had sealed him, drew a delighted gasp from the Omega in front of him. Neither could be sure that Kaeya wouldn’t conceive from this, not when heat made Omegas more fertile, and not when Diluc hadn’t even tried to pull out before giving him the knot. Releasing the firm hold of his teeth on Kaeya’s neck, though, Diluc gave a shaky exhale as he brushed his hair away, not bothering to tug at their hips, given how he could feel Kaeya’s body wouldn’t release him any time soon.

It wouldn’t be last time he’d satiate that need, either. Heats lasted for five days for most Omegas, and Kaeya was.. at best, barely half way through.

A child wouldn’t be the best way to start their strange reconstruction of what they lives together would be now, but it wouldn’t be the worst, either.