What Cally remembers is this:
There's a lot of beer floating around the party, and she's angry and she wants to get back at Chloe and so she drinks some of it, and then she drinks a lot of it, because that's what the girls she knows do at parties. Except Chloe and Lois can hold their liquor, and the thing Cally forgets is that she doesn't even feel it at all. And then she has to fake it, because it's not like she can afford to look that out of place and she's noticed some guys noticing her empties, so she can't risk it. She has to play it up.
And with one thing and another, one of the guys who'd been noticing notices a lot harder, (even she knows the young, rich and brilliant Tony Stark) and she ends up following him up to some room that probably isn't his, because that's why she's here, after all, she's single now and free to do what she wants, and she knows Chloe's busy fucking some guy at another party somewhere, and she needs to know. She needs to know if she can do this with a guy, and she figures a guy with Tony Stark's reputation would be a good place to start.
It's not what she's expecting, at all. Technically the mechanics are the same, she's plenty used to the actual, physical action, but she's not used to so much muscle under her hands, rough calluses on the hands touching her, she's not used to the smell, which is a nice, clean, spicy smell mixed with the sweat but so very different from strawberry shampoo, but most of all she's not used to the feeling of a heavy body over hers, the intimacy of another body driving into hers.
It's better than she thought it would be. After the first time, he sort of slumps over her, heavy and panting, and she thinks, okay, not so bad after all, even though he's still inside her, and it feels weird and is maybe starting to feel sort of gross. Then he laughs, abruptly and breathlessly, and it's so like he's reading her thoughts that she starts giggling too, and he starts to slip out but her body clenches against it, instinctively, and he stops laughing to moan a little, under his breath but loud to her ears, and she feels him twitch inside her. And then he starts to get hard.
Again? she thinks, incredulously, but then he grabs her ankles and puts them over his shoulders. It changes the angle, puts pressure somewhere that it hadn't before, and when he plants his hands next to her shoulder and surges upwards, it's suddenly, shockingly good.
He takes it slow, the second time, and her first orgasm is so powerful for a moment she's afraid she's actually… you know, crushed him, but then she recovers enough to realize that those noises were actually pleasure noises, and just like always her body compensated unconsciously to non-injurious levels of force. For the second orgasm, he rolls her over and pulls her on top, which she likes so much, she stays for the third. For the fourth orgasm, he has her on her hands and knees, and when she's too limp and wrung-out from that one to hold herself up, he pushes her down to her belly and fucks his way to his own blazing finish.
And then the next day Chloe comes into her room, pale and hung-over, and they kiss and make up and Cally says nothing, because she didn't want to hate it but she didn't expect to like it, not as much as she did. Mind over body, she thinks, psychology still trumps biology, and as far as she is concerned she is still a straight male on the inside where it counts, and last night was just an aberration.
Later, as Chloe slowly kisses her way down Cally's belly, she pauses to murmur, "So what'd you do last night?"
And Cally says, breathlessly, "Don't remember," and comes from the feeling of Chloe's girl-soft mouth between her legs, and tries to forget the rasp of Tony's beard against her thighs.