The silence in your office is like a lead shirt; uncomfortable and heavy. The quiet that had preceded Dr. Brennan's statement hadn't weighed nearly this much, but with one statement it seems like the gravity had increased tenfold. You sit in it, waiting for one of them to speak. You want to hear their reactions to what Dr. Brennan has just told you; this is not a time for prying questions.

For her part, Dr. Brennan is sitting straight-backed, looking somewhat uncomfortable, unable to decide whether to continue looking at you defiantly or to glance over at the unmoving Booth. He hasn't looked at either of you since she'd dropped the bomb. His elbows rest on his knees and his face is buried in his hands and if you weren't positive that he had to be conscious in order to sit that way, you would swear that he'd stopped breathing. You desperately want to say something. Your face is aching to break into a big, goofy smile, but you refrain. Obviously, even if based solely on their body language and not on the history you know them to share, this is not happy news.

Finally, Brennan, sick of waiting, sick of not looking at Booth and in a clear state of discomfort, attacks you.

"Why are you just staring at us? Shouldn't you be making all kinds of unscientific conclusions about the reasoning behind it? You can't be a very good psychiatrist if all you do is sit there."

You raise your eyebrows at her and knit your fingers together. There's no way she's goading you into saying something. You know that as soon as you open your mouth, one of them will find a reason to get angry and storm out. And Booth still hasn't moved, so you wait.

"I don't see why it's such a big deal." Brennan crosses her arms and leans back in her chair. A soft, strangled, bitter scoff comes from between Booth's hands. Her eyes flick over to where he still sits, unmoving.

"There's a perfectly good, rational reason behind Booth and I having intercourse." You see a small twitch in Booth's hands and deduce that under them, he's probably wincing at her phrasing.

"I," she pauses, takes a breath, "am considering having a child, and since sperm donors are expensive at best and unreliable, I thought, since Booth is a very good specimen of male DNA-"

"It was a mistake."

You look over at Booth, who has raised his head, finally, but is looking at no one in particular. You sneak a quick glance at Brennan's hurt expression before focusing all of your attention on the FBI agent.

He doesn't say anything else, but stares at his hands, his elbows still resting on his knees. He looks miserable, and you think rightfully so. Having worked with the pair as long as you have, you know the depth of Booth's feelings for his partner, as well as his stance on love and sex. It must be heart breaking for him to hear her talk about it in such unfeeling, scientific terms.

Dr. Brennan recovers herself and replies "Well, I don't think tha-"

This time he looks her straight in the eye, and even Dr. Brennan must be able to see the hurt in his face. "It was a mistake." He emphasises the last word.

The pair don't break eye contact for quite some time. Dr. Brennan looks shocked, and a little hurt, while Booth looks downright miserable. Finally, you decide to speak.

"Why would you say it's a mistake, Agent Booth?"

"Because that's what it is, Sweets. Sex should not be a science experiment. It should be-" he stops himself. He's growing angry and you can tell that he is trying his best to suppress it. He's not looking at Brennan anymore; his eyes are pinned on you.

Never one to give up, he rephrases. "It isn't a means to an end. It is an end. It isn't rational, it's emotional. It's not," he sighs. He's still looking at you, but you know his words are directed at the other person in the room. "It's not science. It isn't goddamn science."

His voice is quiet, but hard. He hasn't broken eye contact, and you're desperate to look at Dr. Brennan. You pull your eyes away and she's stock still and pale. She looks at you, then back at Booth, whose eyes are still glued to your face.

"Anthropologically-" but she is again cut off.

"No, Bones!" He turns his whole body in his chair. "Anthropology is broad! It's history and group study! This-" he seems to suddenly realise that he's raised his voice, and brings it down to a low grumble, almost a growl. "This... last night... that was personal."

She's stunned for a moment, as are you.

"I... I thought that I was clear about... when I..." She never stutters, but you think that even Cam would stutter under Booth's angry, hurt gaze.

"I know Bones," his voice is cold. "I never said it was your mistake."

He looks away from her and stands. He buttons a button on his blazer and turns to face you. He looks you in the eye and shakes your hand. "Well Sweets, it's been a pleasure working with ya. I've got paperwork to get to."

The finality of his gesture makes your heart sink a little. Without looking at Brennan, without helping her into her jacket or suggesting Thai food or coffee, without a shoulder nudge or a smile, he turns his back on you both and leaves the room.

You hesitantly look at Brennan, whose eyes are welling with tears. She is at a loss, and she's not the only one. You open your mouth to say something comforting, to say anything, but you don't. Booth has said it all. She sits for another few moments, presumably to regain her composure.

Finally, she slowly stands up and you don't miss that she swipes at her eyes with a shaking hand before shrugging on her jacket. She stops at the door as if she wants to say something. Her back is to you and she takes a deep breath. Appearing to change her mind, her head drops for a moment.

Then her hand is on the door and she's gone, and you can't help but wonder if you'll ever see either of them again.