Pepper pushes Bruce down into the chair and says, "Sit."
So he sits.
It’s not all that difficult of a command to obey at first. Yes, there's a part of his brain that is graphing the arc of her hips as they sway, wondering what it might be like to fit his palms around them, but it's a fleeting fancy, and doing what Pepper says is always better than not.
She rewards his efforts with a peek over her shoulder and a smile, then turns and shrugs her jacket off. She doesn't bother to catch it, just lets it hit the floor with a heavy thump as she holds eye contact. Her tongue flickers across her lip as she undoes the button at her collar, fingers lingering before she moves them down. Another button follows. And another. Bruce's mind is working overtime in the breathless moments between buttons -- it’s very easy to imagine what it would be like to follow the path of Pepper's fingers with his mouth, to kiss his way down the curve of her neck and into the sharp jut of her collarbone, the hollow between her breasts.
But again, the temptation isn't insurmountable. He just has to focus. He can do that.
Of course, then Pepper turns around and lets her blouse follow her jacket, and Bruce's focus shatters as his breath catches in his throat.
Her back, usually a plane of creamy white dotted with freckles, is covered with a sprawl of equations. They're beautiful. Force and motion are charted in stark black ink, curling around her shoulder blade and meandering across her ribs. The math is elegant, but even more intriguing is that none of these equations are finished and something in Bruce can’t let those variables hang there in space, unsolved for.
Pepper glances over her shoulder at him, winks as she gestures to the integral that’s dipping down under her waistband.
"You like it?"
"Yes." His voice is raspy from the sudden dryness of his mouth. "Very much."
There's a dry quirk to Pepper's smile when realizes what Bruce has missed in favour of mentally balancing his binomials.
"I’ll have to thank Tony for his help later, then."
Oh. Right. While Pepper could probably have come up with these on her own, she couldn't have written these on herself without assistance.
Bruce imagines her lying on Tony’s workbench, on his bed, head pillowed on her arms as Tony bends over her, one large hand splayed on the small of her back for stability as he draws the pen across her skin, marching brilliant equations across her hips, down her spine. His arousal spikes so fast that his vision blurs.
The click of Pepper's heels brings him back to himself. She's standing in front of him now, holding out a marker. When he takes it, Bruce realizes that it’s the same one Tony keeps in the shower for mid-wash revelations. The same as what must be on Pepper’s skin.
"Do you want to finish what he started?"
Bruce pops the cap off. “Yes, please.”
Later, in bed, Pepper is dozing in Bruce’s arms. She stirs when she hears him uncap the marker, smiles indulgently as she lets him scribble one last equation on her belly, just along the bottom angle of her ribcage.
x² + (y - (x²)^(1/3))² = 1
"What’s that for?"
"A thank you for Tony."
Pepper rolls her eyes, then rescues the pen from Bruce's hands.
"Well it's not fair that I'm covered in ink and you haven't got a mark on you."
Bruce twitches backward, laughing, but lets Pepper doodle back in retaliation. He glances down and catches a short, sweet attempt at an equation.
f(x) = 3-|x|
"Less than three?"
Pepper pops the cap back on the pen with a smirk.
"Less than three."
Bruce ducks his head to press a kiss into Pepper's hair and hide his blush at the same time.
"I ... can live with that."