Sara isn't sure when her feelings for Catherine changed. It all started a few months ago with that insane reverse forensics experiment. Sara remembers saying that if she had anything to say to Catherine, she would say it in private. And she had done just that. She had gone to see Catherine in her office later that night, and they had ended up having another one of those famous arguments. Sara can't quite remember what she said, but she can remember that Catherine slapped her. Surprisingly hard. And then they were kissing. Moments later she was on her back on Catherine's desk. Catherine's hands were everywhere and Sara's skin was on fire. When she came it was unlike anything she had ever felt before.
So recently, every time they've had an argument, they've resolved it with sex. Urgent, quick, hard fucking. In Catherine's office, in the locker room showers, in one of the cars. Even in Sara's lab. Hands and mouths everywhere, moans and gasps and whimpers. And then silence. They have nothing to say to each other, not until the next argument erupts. Which it inevitably does.
Tonight, Sara watches Catherine doing paperwork in the break room, and all of a sudden she really wishes she was going home with her tonight.