It begins as Arthur's honest accident.
He's been working for hours on end, attempting to clean up the paper trail from their latest case-gone-messy. Eames' first name is their little secret, usually used in their apartment at home—and although Eames never told him not to divulge his name, it's something Arthur likes to have all to himself.
His pen rolls off the conference table and falls right next to Eames' foot. He is exhausted, has a horrendous headache, and isn't thinking clearly, so it's a reflex when he asks "Will, can you get that for me?"
Eames looks down from his own laptop, spots the pen, and hands it back to Arthur without another word. In fact, the slip-up probably would have gone unnoticed if Ariadne hadn't been pointedly staring at Arthur.
"What?" he asks, slightly defensive. "Why are you looking at me like that?"
"You called him Will," she says, gaping at Arthur. "Not Eames, Will."
"That is my name," Eames says smoothly, seemingly unbothered. His fingers continue to fly over his keyboard, no hitch in his movements. "Something the matter?"
"No, sorry. It just surprised me a little." She bites her lip, grinning. "So, I take it Yusuf was right?"
Yusuf looks up from where he is packing up his portable lab equipment. "Right about what?"
"That Arthur and Will are fucking," she says gleefully. "So, what's it short for? William?"
"Fitzwilliam," Arthur corrects. "And we're not fucking, we're dating."
"Dating and fucking," Eames proclaims, grinning cheekily. Ariadne squeals with delight, and Yusuf chokes on his coffee.
"Dammit, Eames," Yusuf says. "I really didn't need that mental image."
"Oh, hush," Ariadne says. "You brought it up. So, you two are, like, Darcy and Elizabeth? Except for the whole guy-guy thing."
Arthur crumples up a piece of paper and tosses it at Eames' forehead. "Fitzwilliam Darcy and Elizabeth Bennet, you uncultured swine. Pride and Prejudice, Jane Austen? Your national heritage in literature?"
"Ah." Eames shrugs. "My little sisters loved that book; I never read it. I was too busy in the military academy to steep myself in the classics."
"It's actually pretty good," Yusuf admits. "Very snarky, subtle humor. I read it in college."
"It's so you," Ariadne says, eyes shining. "Except I think Eames is actually more Elizabeth, and Arthur is more Darcy."
"That's unfair." Arthur frowns. "I'm not nearly as arrogant as Darcy."
Ariadne looks like she's going to contradict him, but Saito interrupts her as he enters their workspace. "How close are we to finishing, gentlemen?"
"Nearly done. I need to make some minor…adjustments, but nothing that can't be done from the plane," Arthur says, still frowning. "The only question is how long it's going to take us to pack up the warehouse."
"Not long," Yusuf says. "I need a few people to help me get this stuff in the van, and then we can go."
Saito smiles and snaps his fingers. A team of local workers jogs in, picks up Yusuf's boxes, and begins to cart them out to the van.
"Ten thousand a year," Yusuf whispers, and Arthur snorts before he can help himself.
Three hours later, they are on the plane ride home. Eames is working his way through Pride and Prejudice, and Arthur is putting the finishing touches on the cleanup of the operation. Finally, Arthur shuts his laptop and places it back in his briefcase, shoving the whole thing under the seat in front of him. He closes his eyes and lets his head drop to Eames' shoulder, and is drifting off to sleep when he hears Eames' voice.
"I cannot fix on the hour, or the look, or the words, which laid the foundation," Eames whispers, tilting his chin to kiss Arthur's forehead. "It is too long ago. I was in the middle before I knew that I had begun."
Arthur falls asleep smiling.