You Oughta Know by Meow

Arthur and Eames get drinks and agree that they are very mature and totally past all of the weirdness from the past

But they aren't.

So first, this is not an age difference that is especially meaningful - I really can't remember if I ever specified, but I would say it's 6 years MAX and probably something like 5 or 4 years 8 months, because even though Arthur seems like this fully formed, mature adult to Eames when he first drags him home from off the street, I'd say he's 21, maybe, precocious himself, and in that stage of life where you still know everything and think you're grown. 

So I don't know what the age difference is, but you know who does? down to the DAY? uh, Arthur and Eames, who both know it's this Huge Looming Thing that Can Never Be Reconciled:

Eames who's coming up on thirty and when he sees sixteen year olds they're babies, he can't even imagine sleeping with one of them, and he's retroactively burning with embarrassment about trying to sleep with Arthur, GOD, that must have been disgusting. Or maybe not even disgusting, maybe Arthur just thought it was funny, or something. pathetic. 

And Arthur notices that Eames is too careful with him-- takes pains over being professional and friendly and Arthur's not stupid, he understands that this is a Boundary, that Eames is politely (kindly, even) keeping Arthur at arms' distance. and Eames is so perceptive, he probably knows, GOD, he knows that Arthur thinks about him That Way sometimes and he honestly, he tries not to, he tries and it's really difficult because Eames is so--! Oh, tall and smart and built and so gorgeous it makes your eyes water and Arthur knows that it's wrong for him to feel That Way about Eames. (And is so consumed by shameful lust he's oblivious to the fact that Eames knows he's a loser compared to Arthur, who is so hot--beautiful, really--and clever, a genius, knows everything and everyone and--)

So many assumptions and regrets and tangled feelings and they're made for each other, right? The premise of this story is they're made for each other and irresistibly attracted to each other and OF COURSE they start having sex before figuring any of this out and BOTH of them think they're taking advantage of the other one, like Arthur knows he's basically a sex offender and Eames knows Arthur just feels sorry for him and both of them know that if they were a stronger, better person, they would stop, here, I even had this in a section labeled OH JEEZ EAMES & ARTHUR START TO DO IT

“Hey,” Eames says. “You know I’m not a horny kid anymore, right? I know that I’ve been looking at you and I’m sorry. it’s--rude. You’re just. I’m not going to jump you or anything, so you don’t have to keep leaving while we’re trying to get some fucking work done.” “You’ve been looking at me,” Arthur repeats. “Yes, I know,” Eames says. “I don’t mean anything by it, I’ll get past it, I just. want.” Arthur licks his lips. He feels a little light-headed; it’s the most attention Eames has focused on him since that first day. Eames flinches, staring at his face. “And if you could stop doing things like that, it would probably help--” “Like what?” Arthur says. “Like licking your fucking pretty mouth, like touching me or, making me think about holding you down and fucking you until you look at me,” Eames blurts out. “Sorry, fuck. I mean, sorry that was really unprofessional.” Arthur nods in agreement. He needs to get out of here. He licks his lips again, by mistake. “I didn’t mean to make you uncomfortable,” he says. He’s rehearsed this, a little, in the bathroom, staring at himself sternly and telling himself to get it together, so it comes out pretty smoothly. “I would never act on--or expect,” he falters, because Eames is looking at him. “It’s not you making me uncomfortable,” he says, slowly. “It’s me, I’m making you uncomfortable. Right?” “You didn’t do anything,” Arthur says. “Stop looking at me like that or I will,” Eames says. His eyes are wide and dark and afraid. “Arthur,” he says, and then he puts one fingertip softly against the exact center of Arthr’s lower lip. Nothing happens for five seconds, ten. Then Eames moves his finger, just barely, drawing it in gentle, random pattern and Arthur licks his lips and his tongue touches Eames finger and without really understanding how it happened, Eames’ finger is in his mouth and he’s sucking on it. “I--” Eames says. He looks shocked; his mouth is open.