Title: Cycles
Pairing: Bones/Spock
Rating: PG-13/R
Warnings: kinda cracky, AU
Notes: Followes after Blood. This was written second, but happens...third? I think. So far. So read Blood first if you haven't.
I'm in-between finished prompt fills, but I've got a limited posting window due to computer problems.

Notes v.2.0: Hello FF.N! Sorry I've been late putting this up here. I'm going to try and put most of these up today before I forget. Meanwhile, enjoy!

Summary: While the Enterprise is stranded and low on supplies, Leonard's biology rears it's ugly head for the first time in years.

Leonard officially hates his biology.

The meds mean he can't really time his cycle. He thought he was in the clear, so the supply shortage that meant he couldn't synthesize another treatment was inconvenient but nothing to worry about. Because the universe hates him, it turns out he's wrong.

It's subconscious at first. He stands in ways that display his hips or his stomach more. If he was one of his ancient ancestors and naked, he'd be flashing what looks like a dark purple bruise on his stomach to show how fertile he is and how flat and prime for impregnating he is, and the entire thing is ridiculous.

He doesn't notice until he licks Christine. He'd been moodier than usual, but he'd assumed it was just a side effect of coming of the meds. If he'd been snapping more than usual, he'd just make it up to whomever when they got out of this mess.

But he's yelling and in her face and then he grabs her and licks her, one long stripe up the side of her face. She looks disgusted and worried and horrified. Then she slaps him, and he doesn't care because he deserved it and most of his attention is on "Oh my God" and wondering how long he has before he needs to take himself off duty and lock himself in his quarters.

Not long, apparently, because he licks Jim a few hours later.

Jim's surprised and amused. He's also disappointed when Leonard scowls and crosses his arms over his stomach, swearing. "I cleared you for STDs three days ago! How've you managed to pick something up again that quickly?"

He gives himself three days.

Make that one. He licks Nyota.

He doesn't immediately pull away either. She's…nice. Good genes. And she's pretty. He considers licking her again, but her reaction surprises him.

When he doesn't move away, she clicks her teeth at him. Firmly. As if she's seconds away from tearing into his neck if he doesn't back off because she is not interested.

He pauses again because he's surprised, and her confident stance cracks a bit. After a moment, she shifts. "Did I do it correctly?" she whispers.

He nods slowly and moves so his arms aren't blocking her. "How did you…?"

"I made a point to study various come-ons from different species. I wanted to know how to tell them to back off."

He believes it.

"Why have you never…gone through this before?"

Leonard makes sure the corridor they're in is actually empty before he replies. "I was taking something. This is the first time."

She frowns. "They let you?"

"It wasn't 'their' decision."

She wants to ask, he can feel it, but she doesn't push the issue. "Do you have somebody?" she asks instead, and fuck. If he had anyone to mate with, why would he be wasting his time licking her?

He doesn't have to say anything out loud; apparently is face is enough.

"I thought you and the captain…"

"Where on earth did you get that idea?"

She starts to say something and stops, clearly rethinking her answer. "Never mind," she says. "What are you going to do?"

"This thing should last for about a week more. If no one tries to die between now and then, I'll lock myself in my quarters until it blows over."

"Are you sure that's a good idea?"

He shrugs. "It's the best option here. Either I'm annoyingly horny and miserable for a week or I risk losing control of myself and raping someone."

"I doubt it'd come to that," she says. "Tserillians are good at respecting boundaries."

Leonard snorts. "I wouldn't be so sure of that."

Nyota shrugs. "You aren't full Tserillian, and I'm assuming you didn't grow up in a strictly adherent household."

Voices approach from the end of the corridor. Leonard makes a face. "I'm gonna finish my paper work and give up. Sorry about the…"

Nyota smiles. "It's okay; I'm kind of flattered. If you don't mind, I'll check on you later."

He nods and tries not to leer at the passing ensigns as he makes his way towards his office.

Being safely cooped up in his quarters is irritating as hell, but there hasn't been any licking and he isn't pregnant so it works out. Nyota stops by to make sure he still gets food – because he isn't leaving his room for anything short of half the crew dead or dying of something other than their own stupidity. He's horny, and he's wound up tighter than a corkscrew, and he feels like his skin's on fire, but other than that it's nothing he can't cope with.

He thinks he might be able to get away with this until Spock arrives.

He doesn't even hear what the half Vulcan came to say. Leonard leaps on him, sending Spock reeling back in surprise. Leonard licks him, and it's good, and he's on fire, and he licks again and reaches out desperately with his mind because fuck it his control's shot to hell, and the bastard tastes good, and Leonard finds himself mouthing the warm skin on Spock's face, fingers clawing at everything he can get.

Spock's mind swirls against his and reaches tentatively back. Dr. McCoy?

"Leonard," he gasps. "Want you. Hot."

"Doctor what is wrong?"

Leonard grasps at the relevant information and pushes until it's close enough to being in Spock's mind, too preoccupied with trying to get Spock's hands on him, trying to get Spock to kiss him back.

He needs Spock to know about the Blood and the gift and the burning and he needs.

"This is not how I had intended to go about forging a relationship with you."

Spock sounds mildly annoyed, and Leonard would wonder about that if Spock's hands weren't under his shirt and Spock's tongue in his mouth.

It feels so good. Leonard needs, and Spock is good, and everything's…

If they're going to do this he needs to do something else. Leonard flounders for a moment, torn between devouring his mate now that he's finally got one and making it to the drawer that held the last minute contraceptives he hadn't thought he'd really need.

He can feel that Spock is curious about his psi-ability, that after they've finished this Leonard's going to get the 3rd degree. Leonard's okay with that, so long as he gets the sex first. Lots of sex. Days of as much sex as possible, because fuck it he's horny, and he's going to be horny for a very unfortunate amount of time.

Spock finds the hypo and administers it himself when Leonard's too distracted to do it. Leonard thanks him by grinding against him.

"You are certain?" Spock says when Leonard begins to fumble with his pants.

Fuck. "Bit late for that," he gasps, and mentally adds Should be asking you.

"I still believe it would be best to establish it now." Spock says. With his mind he adds You are aware that Vulcans in general do not partake of casual sex?

Tserillians mate for life. The stronger the Blood, the more likely a part Tserillian will follow a similar pattern. Another time, Leonard would be able to have sex no strings attached, or marry and divorce as he had, but this is burning, and the sex wouldn't do any good without the connection.

He pushes the information at Spock; it would take too much effort to say aloud and he had other things on his mind, such as getting his partner naked.

"So long as we understand each other."

Spock's fingers are on Leonard's face, and then their minds swirl together, and it's such a relief Leonard comes in his pants like a teenager.

"More" he says, out loud and in his thoughts, and the edges of the world blur a bit. Everything is Spock's hands, Spock's skin, Spock's mind tangled with his.

Leonard wakes from a haze of lust and need feeling sore and embarrassed. Spock's meditating on the floor beside the bed, his mind a comfortable weight in the back of Leonard's mind.

Part of Leonard is uneasy with the concept of having someone in his mind. If his biology didn't have a mind of its own he'd never have accepted such an offer, let alone initiated the contact.

Spock's presence is nothing like he remembers. It's warm and small. Leonard is space, and Spock is the shuttle, but no one is trapped inside anything. He needs a less loaded analogy.

Spock's curiosity is a faint itch under his skin, but the part Vulcan says nothing. He does, however, open his eyes when he sees Leonard watching him.

"Are you still willing to proceed with this relationship?"

Leonard shrugs, deciding honesty is the best policy at this point. He has his reasons for shying away from mental contact, but those reasons have nothing to do with Spock and everything to do with things he'd rather not think about. He doesn't know how he's going to handle this in the long run, but…this link between them isn't going anywhere - it can't, that he knows of – so he'll have to make the best of it.

Out loud he says "We'll see."