Here's how it goes:
He's already down there, licking the base of Rodney's cock, kissing his balls, nosing around beneath them; he slides his tongue a little lower. "Can I?" he asks, mostly out of courtesy. Rodney doesn't have many hang-ups -- he once stuck his entire hand up John's ass -- so it's a surprise when Rodney squirms away from him and nearly falls off the bed protecting his virtue.
"That's disgusting!" Rodney says, clutching the sheet to his nipples like that's the part John's after.
John tries reason. "You like my fingers there."
"But your mouth -- ugh, it's so unsanitary. I'd never be able to kiss you again!"
John tries more reason. "There are ways around that, you know. We could take a shower first. C'mon, you'll like it."
"No, I won't," Rodney says, crossing his arms over his chest. "Now finish my blowjob, and you'll probably have to start over because I've received a nasty shock and that is not conducive to maintaining an erection."
Rodney's a big fat hard liar and John gives him an extra wet blowjob just to be spiteful, letting his saliva drip past Rodney's balls and down into the forbidden zone.
The next time they're in bed, Rodney limp and panting from an especially fantastic orgasm, John tries again. He pillows his head on Rodney's stomach and trails his fingers up Rodney's thigh.
"I want to do this for you, Rodney."
"Mm," Rodney says, shifting into John's hands.
"It's not dirty, not in the way you think, and it's so hot." He mouths kisses across Rodney's belly. "We can stop if you don't like it, but you will, I promise."
Rodney sighs and his legs fall open and John thinks he might be getting somewhere, except Rodney's on another page entirely -- sound asleep and dreaming.
"Just stop asking, Colonel! No means no!"
"I let you put your hand up my ass."
"And you complained the entire time."
"Because you were gloating, you obnoxious fuck."
"Oh, like you wouldn't gloat. You said you weren't going to like it."
"And I tried it anyway, didn't I?"
"This isn't even remotely the same situation! You're clearly wrong --"
"Just once -- just once I'd like you to consider my ideas might have some value before dismissing them out of hand!"
"Maybe I would if you ever had a good one!"
And then John slams him against the wall and they have angry sex. John doesn't apologize for calling Rodney an obnoxious fuck -- because he is, he so is -- but he does stop asking.
Things mostly go back to normal after that.
John can't stop thinking about how hot it would be to get Rodney on his stomach and lick him until his jaw aches, but John's not going to push, at least, not until he has some leverage. He thought the fisting episode would get him some points, but apparently in Rodney's book, that counts as a strike against him since he wasn't sure about it.
But then something weird happens. Rodney starts turning down blowjobs, apparently not trusting John to keep his tongue to himself. Or, and this is far more likely as Rodney doesn't have a problem saying no, not trusting himself not to give in and nudge John, and his tongue, downwards in the middle of a blowjob. In Rodneyland, the solution to this is to remove the temptation entirely.
It's a huge tactical mistake. Rodney loves blowjobs. He likes them in supply closets, in public restrooms, outside, inside, while sitting at his desk, clothed, or not, but most of all, Rodney loves blowjobs in bed, loves reclining naked on a stack of pillows and watching John suck his cock.
Rodney will never survive a blowjob embargo and John knows it. He quietly escalates the war, beginning a campaign of blowjob terrorism guaranteed to bring Rodney to his knees. Never in his life has Rodney McKay been offered so many blowjobs, so often or so lovingly. It's killing him to say no, and after a week of that Rodney looks like he's going to explode. There is nothing he hates more than admitting he was wrong, and this is the look he gets right before he breaks.
"Fine!" Rodney says, in the middle of lunch, interrupting Zelenka's story about a slap fight he witnessed between two of the anthropologists. Rodney slams his jello cup down. "If it's so important to you, I'll let you do it!"
"Do what?" Zelenka asks.
The tips of Rodney's ears turn bright pink. "Uh, nothing -- the Colonel wanted me to -- uh, he was going to, to --"
"Teach him how to juggle," John says easily. "It's more fun with two."
Zelenka peers at Rodney suspiciously and Rodney stammers something about leaving an Ancient hot plate on in the lab, grabs his jello and runs out of the mess.
"He is acting even more oddly than usual," Zelenka says.
"Oh, you know Rodney," John says, eating the other half of Rodney's abandoned sandwich. "He hates doing things he might not be good at."
After lunch, John messes around in his office for a while (deleting emails, losing paperwork, the usual), goes for a run with Ronon, promises himself to never go for a run with Ronon again, then gets up off the floor and heads back to his room for a shower. He finds Rodney there, sitting on his bed, hunched over and miserable.
"Hey," John says, "what's wrong?"
"You've been after me for months to do this, and I said I'd let you, but do you come running after me gratefully? No. I've been sitting here for almost an hour!"
"I didn't know you meant right now."
Rodney sticks his pointy nose in the air. "I wanted to get it over with."
"Jesus Christ," John says before he can stop himself. He sits down next to Rodney. "You're really something."
Rodney clearly can't tell if that's a compliment or not. He crosses his arms over his chest. "Are we going to do this or not?"
"Yeah, I'm thinking not," John says, wiping his face on his sleeve.
"No? But -- but you said --"
"I said we didn't have to do it if you didn't want to. You don't look like you want to. I'm taking a shower." John strips off his sweaty t-shirt and leaves Rodney sitting on the bed.
Ancient showers don't have doors. You just turn the corner and there you are. John drops his dirty clothes on the floor and steps inside. The water's the perfect temperature and he's washing his hair when Rodney appears from around the corner, still fully dressed and getting a little damp.
"I do, want to," Rodney says, looking resentful and confused.
John suspected as much. Rodney made these kneejerk decisions and then couldn't back out of them gracefully on account of what an asshole he'd been.
"Take your clothes off and get in here, then."
Rodney strips and then stands against the wall as if he's pretty sure he doesn't want to dance, but wants someone to ask him all the same. John rinses his hair, grabs the soap, and tugs Rodney over. "C'mere."
John gets them both nice and soapy. He likes the way the bubbles get caught in Rodney's chest hair, the way they slide down his stomach to his cock, which is looking about half-interested. Rodney, on the other hand, is still looking skittish, even though this isn't anything they haven't done before. John brings him close and kisses him. Rodney relaxes a little, leaning into him and kissing back, big hands gripping his hips as John slides two soapy fingers down the cleft of Rodney's ass. Rodney makes a breathy sound.
"You okay?" John asks. "You're so quiet."
"Yeah, just, more of that, that's good."
John spends a good fifteen minutes soaping Rodney's ass, cupping the cheeks, running his fingers between them, carefully rubbing around Rodney's hole, going a little inside. Rodney's fully hard now, leaving love bites along John's collarbone, and offering his usual moans and attempts at micromanaging. John kisses him, happy to see he's finally enjoying himself.
"I think that's enough," Rodney says. "My ass is so clean you could eat off it."
John bites his lip, manfully trying to suppress a fit of the giggles, and Rodney rears back to point at him viciously. "Don't say it. I am leaving right now if you so much as --"
In order to protect his chances of getting laid, John is forced to push Rodney under the showerhead, where he sputters and curses John out. John makes sure he's thoroughly rinsed and squeaky clean, gives himself a good, quick washing just in case he gets really lucky tonight and shuts the water off.
They forgo the towels and use the Ancient hot air driers, which don't work all that well if you have to get dressed afterwards because they always leave a few damp spots, but they're fine if you're headed straight to bed.
"I feel like I'm in a car wash," Rodney complains, hair standing straight up. John finds Rodney's receding hairline way more arousing than is probably healthy. Okay, the truth is, he probably finds most everything about Rodney more arousing than is healthy. John sort of has a thing for him.
They stretch out on the bed and kiss for a while, and then Rodney starts shoving John's head down, the universal signal for "blowjob right now." Since Rodney's been on a self-enforced blowjob sabbatical for almost a week and a half, John cuts him a break and gives him a nice long suck, deep throats him, swallows around the head, and then pulls off. He doesn't want Rodney to come yet. Orgasm is the fastest way to put him asleep, short of a knock to the head. Rodney whines in complaint, but John gives him a little smack on the ass.
"Roll over," John tells him.
He does, showing John that fine ass of his and John takes a moment to be smug now that Rodney can't see him. No wonder Rodney likes being right so much; it's a total high. God, he's wanted to do this for months, and now here's Rodney, butt in the air, all his. He palms both cheeks and gives them a little squeeze.
"Do we need a safe word?" Rodney asks, face pressed into the mattress.
"You can have one," John says, generous.
"Or," John says, "you could just say no and fall off the bed like you did the first time."
"I didn't actually fall off the bed," Rodney sniffs.
"Whatever." John grabs a pillow and tucks it under Rodney's hips. Rodney wiggles around, getting comfortable, and John's not waiting anymore; he leans in and gently sinks his teeth into the bottom curve of Rodney's ass. Rodney jerks in surprise, but he likes being bitten, John knows, so he nibbles around down there before adding his tongue in, broad strokes over the top of his cheeks, slowly edging down toward the center. Rodney's still wiggling around and John doesn't know if it's because he's uncomfortable or because he's enjoying it, but he isn't asking to stop, so John squeezes his ass again, uses both hands to hold him open, and licks right across his hole.
"Ah!" Rodney says. "That's, that's --"
"What?" John stops where he is, pretty much speaking directly to Rodney's ass.
"I don't know," Rodney says, frustrated and squirmy. "Do it again!"
John does it again. He licks with the flat of his tongue. He licks straight lines, little circles, a big X right over Rodney's hole.
"Yeah!" Rodney says, apparently deciding he likes it. "More of that, with the pointy tongue, that's good, right -- oh."
John gives him the pointy tongue, and the broad strokes, and a little hint of teeth, and Rodney's up on his hands and knees now, shoving his ass eagerly into John's face, begging for more, and John gives him that, too, shoves his tongue into Rodney's ass and loves it, wants to do it all night, until his jaw aches, until Rodney says --
"It's good, it's good, it's so good, don't stop, you were right, you were -- oh god, you were right."
Next time Rodney's the one who asks.