Summary: Greg is an Omega. This is slightly problematic with his job, but he's finally got everyone convinced that he doesn't need an Alpha to be able to do his job. His heats are regular, allowing him to spend that week at home. Everything is going good until Sherlock Holmes shows up on his doorstep the night before his heat. Sherlock's on suppressants, meaning that Greg doesn't have to worry about being forced to bond. What will happen when he learns that Sherlock wants to bond?

Written for a prompt on the kink meme.

Thanks to SaliorChibi for helping me flesh out the prompt :) If you haven't read their stuff, you should, as they have some of the best Sherlock fics I've read so far

Greg's just finished stocking the minifridge in his room with the fruit and sports drinks he had just bought when there was a knock at the door. Frowning, he goes to answer it, wondering who in the hell would be bothering him tonight. His heat begins tomorrow so he has the week off work, as he always does this time of year. No one would call him in for a murder now, and he has no close friends. Who the hell would be calling on him at 11'o'clock at night?

He gets his answer when he opens the door and finds Sherlock Holmes on his doorstep. The mad bastard had only been helping them with cases for two months, but already Lestrade's solve rate has gone up. Still, he really didn't want the other man visiting him right now.

"Sherlock, what…?" he starts to ask, but the other man ignores him, stepping inside the door and closing it behind him.

"I need a new case Lestrade," Sherlock drawled, shucking out of his coat and hanging on one of Lestrade's pegs. "I'm bored, and no one else at the Yard will work with me. They said you wouldn't be in for a week."

"I won't be Sherlock, I…" Greg tries, but he gets no farther. When Sherlock had entered, Greg had backed up. Now, the younger man had approached him, bringing him in close enough proximity to get a good whiff of his scent, his Alpha scent. He feels heat pooling in his stomach, which is beginning to cramp. He can feel the emptiness, the need to be filled and fucked, beginning.

"No," he mutters, taking a step back, "No, no, NO!" He practically yells the last, but he doesn't care. He's worked hard to get where he is, proving that he's more than just a breeding machine. He's proved that he doesn't need protecting, that he doesn't need to submit to anyone. He's done a damn good job proving that, and now his body is deciding to betray him, all because Sherlock Holmes, fucking Alpha Sherlock Bloody Holmes, picked tonight of all nights to show up.

"Lestrade," Sherlock said, actual concern in his tone. Greg is apparently the only person who hasn't bored Sherlock enough to make him leave. At this point, Greg wishes that he wasn't so fascinating to the other man. "Greg, what's wrong?"

Greg barely notices the use of his given name, as Sherlock had moved closer and Greg was lost in his scent. Alpha and something else, something odd, as well as the old books, random chemicals, leather, and tea smell that is Sherlock Holmes. The empty feeling increases, and Greg can feel the back of his pants getting damp. Shit, he's leaking already?

"Greg, what…?" Sherlock asks, but pauses as he gets a whiff of Greg's scent, the Omega pheromones stronger than ever. Understanding flashes in his pale blue eyes. "You're in heat. That's why you took the week off; to handle your heat."

How is he that calm? Most Alphas confronted with an Omega in heat would have already tackled him to the ground and tried to get his clothes off. Sherlock's just standing there, watching him with faint curiosity overriding his previous concern.

"What…?" Greg asks, trying to figure out why Sherlock hadn't mauled him. He's distracted by the maddening empty feeling, and before he can consider it, he's unfastened his trousers, pulling them and his pants down so he can reach behind him. The first touch to his entrance is maddeningly light, the muscle already loose and slick with his fluids. He immediately shoves two fingers in, moaning in relief, even though the feeling is still there, just not as strong. He'd forgotten about Sherlock completely, until the other man cleared his throat.

Greg jumped, startled. Sherlock was standing there, a faint blush on those high cheekbones. "I think it would be best if I left now Greg."

Suddenly, Greg doesn't want the other man to leave. He knows that before he had some reason for wanting Sherlock to go, but now all he wants is for Sherlock to mate with him, to knot him and make this horrible empty ache go away. So, as Sherlock turns to go, Greg grabs onto his arm with his free hand. The lucid part of his brain, which is getting smaller every second, is embarrassed at the sight he must be, pants and trousers around his ankles, two fingers still in his arse, cock hard and weeping pre-cum copiously. The hormone-filled haze that has descended on his brain makes it very hard to care about that.

"Stay," Greg begged, tightening his grip when Sherlock tried to pull away. "Please stay."

"Greg, you don't mean that," Sherlock said, trying to free his arm without hurting Greg. "You're in heat; you're just reacting to my scent. You don't want to bond, and I couldn't knot you if I wanted to."

That cleared the fog from his brain a little. "What?" He realized he was still basically fucking himself on his fingers but couldn't bear to stop. The emptiness was there, and his fingers were doing nothing to stop the feeling, but they were better than nothing. He remembered the toys in his room, and just the thought of the knotting dildos cause him to pick up his pace. It's difficult to focus on Sherlock when he speaks again.

"I despised being controlled by my instincts, especially if I came into contact with an Omega in heat, so I made a suppressant, allowing me to control my Alpha instincts. It's the only reason I haven't thrown you to the floor and fucked you through it by now," Sherlock said dryly.

Greg moaned at the thought, Sherlock fucking him with his Alpha cock. "Oh God Sherlock…"

"Do you have toys to help you with your heat?" Sherlock asked, ignoring the way his trousers tightened at Greg's moan. While he's able to control his Alpha side, he can't deny that he's always loved Greg's scent. Coffee, fresh paper, cigarettes, gasoline, and something that was undeniably Omega. Now, the Omega part of his scent was richer, more dominant than the rest. He would never, never tell Greg how attractive he was, especially since he knew how Greg felt about mating. Sherlock couldn't blame him; he'd always thought mating was distasteful as well. Now, however, he can think of nothing better than mating with Greg. It's not a new thought, but it's one he shoves away resolutely while he waits for Greg to collect himself enough to answer. He won't violate the other man's trust now, especially not now when he's at his most vulnerable.

"Um…" Greg says, trying to think. "I have stuff in my room, all ready for my heat."

"You can stay in there comfortably for the entire week?" Sherlock asks, already beginning to shepherd the older man in the direction of his bedroom.

"Yeah…" Greg says, trailing off as Sherlock picks him up. "What…?"

"You would have never made it at your pace," Sherlock explains, easily carrying the DI to his room and laying him on the bed. "Now, stay in here and don't come out till your heat is over. I'll stay to make sure no other Alphas try to get to you while you take care of yourself."

"You could always take care of me," Greg said, groaning as he withdrew the two fingers in his arse and replaced them with three. "God yes!"

"I don't think that would be wise," Sherlock said, turning and leaving the room before he does something they would both regret. He won't take advantage of Greg, no matter how he feels about the other man. If part of his heart broke as he left the DI alone during his heat, well, that was his business. He's not going to muck up this friendship.