Spoilers: CoE, "Day 4" (so that's your warnings right there, although story takes place right at beginning of episode, not at the end).
Notes: Part of Seven Times Jack Shagged Ianto Silly as spawned in the comments at tw_gleeclub and written by 7 different authors. All the parts are going to be linked in one place later this weekend, and I will add that here, so you can read the 7 pieces of the story together.
They don't even get out of the warren of warehouses before Jack swerves the car off the road so abruptly that, for a moment, Ianto's sure he's about to intentionally ram it into one of the other buildings.
“What're you --”
Jack grabs his face and cuts him off with a kiss, so hard and, well, random, that Ianto can't even properly respond. Ianto almost feels guilty, because right now, everything really needs to be perfect, because nothing's been perfect between them or the planet or the stars for a damn long time.
“Don't say anything,” Jack says against his lips.
Ianto struggles against it, but starts laughing anyway. And then Jack does too.
“Are you out of your mind?” he hisses at Jack, who seems too frantic to get their trousers open particularly efficiently.
“End of the world --” Jack says breathlessly.
“Getting end-ier,” Ianto notes.
“A few minutes. It doesn't matt --”
“It matters,” Ianto says, placing a hand over the one Jack has just managed to get half inside his trousers.
Jack stills for a moment and blinks at him, clearly not getting it.
Ianto rolls his eyes. “Thank you,” he says.
This time it's Jack who starts laughing first.
“Shut up,” Ianto says fondly as Jack fists his cock and flicks his tongue in that small, perfect spot just behind Ianto's earlobe.
“You too,” Jack murmurs against him.
“Yeah,” Ianto says, before surging forward so he can shove both his hands down Jack's pants.
After, they tidy themselves as best they can, still snickering occasionally and not quite looking at each other, as if they've suddenly gone shy.
Ianto sighs, as one doesn't just walk into Thames House at the end of the world looking rumpled, but there's not really much for it.
As Jack pulls the car back onto the road, almost as abruptly and dangerously as he pulled it off, Ianto tilts his head back against the seat and closes his eyes, and smiles at the feel of the sun on his face. This moment is nearly all he could have ever asked for: a flash car, a tolerable suit, and I will die smelling of you.