Sometimes there was a vacant look in his eyes. No scrap that... Often there was a vacant look in his eyes, if she was completely honest with herself.
It didn't matter if they were at work, at a restaurant or in bed together. He'd be looking at her, but not at her. She couldn't help but know who he was thinking about.
Unfortunately for Cam, she was in love with Seeley, even if she knew their relationship was just sex to him. Just a body next to him in bed, while he was thinking of someone else. But even she knew that person was unattainable.
Cam had never been a quitter, she never would be. She isn't ready to give up on Seeley yet. She would take what she could get. She knew one thing, she had one up on Brennan. Hers and Seeley's past. She was holding onto that shred of hope.

Booth's world had changed forever, and without realizing it, so had he.
He realized he was just a man, that he could fall.
He'd shown Brennan his weaker side at times. She brought out another side of him, a side he thought had been erased after the war. A side where no matter what he did, he did it all for her approval and trust. He needed it, like he needed air.
He could never break that trust she had in him, after all she had seen and been through with people she loved. That bastard Michael had humiliated her in front of a room of people, and used her innocence and trust in him against her.
Her parents just left her. Her brother packed up and left. Then her father and brother had only just left her, again. He could never hurt her like that. But never is a promise, and she didn't need a lie from him.
He loved that she hugged him when she was scared. It was like she was holding the last breath she would take, then when she was in her arms, everything just disappeared. It was like she was silently screaming to him to beg her broken heart to beat again. That only he could help mend it.
Booth woke from his thoughts. Cam was talking to him. He'd been "uhuh-ing" and nodding through the whole conversation apparently. She hadn't seemed to notice he wasn't listening though. Which was both a sad and good thing.
He felt for Cam, he couldn't let this go on for much longer. He was using her, and felt guilty for that. And also felt a huge sense of dread that Temperance would find out. That could be the undoing of his and Brennan's relationship.

Cam knew that look. He was thinking of her again.
She had no idea what he saw in Brennan. Yes, she was a brilliant woman. And, yes she was attractive, if you like that sort of thing.
Why are you thinking of her now, Seeley? You're with me, can't that be enough? Obviously it wasn't, and the worst thing was, she didn't know why.

"Cam," Seeley interrupted her mid-sentence. "We need to talk."
"We are talking, Seeley," Cam said with a tight lipped smile.
"No, we need to talk. About us..." Booth said cautiously.
Cam's face turned white, then she quickly masked it with a smile.
"What about us? I think we're doing quite well with what we have at the moment." She winked suggestively.
"That's just it, Cam. I can't do this anymore. It's not fair to you or me."
Cam's blood flashed hot with anger suddenly. "Not fair for me? Or to Dr. Brennan?"
"Where does Bones come into this, Cam? Bones and I are just partners." But Booth said it a little too quickly.
"Don't give me that, Booth. This is me you're talking to. I know when you're thinking about her. I can see it in your eyes. Like not too long ago, you were lost in your thoughts, then came back to the conversation like you'd just woken up. I see it at work. As soon as she walks in, no matter what you're doing, you'll straighten up and focus on whatever she has to say." She looked closely at his face to catch his reaction, she saw the caught-out expression before he quickly hardened it.
"Look, Cam, it doesn't matter what you think you can see, nothing is happening with me and Bones."
"Yeah. Well not yet anyway, right Seeley?" she said, with a weary bitterness; she was losing the battle, and she knew it. "But you know as well as I do that's what you really want."
"It doesn't matter what I want, what matters, is what's best for Temperance. Until she says that's me, then nothing is going to happen," Booth said with a sad look in his eyes.
"You know she's unattainable right?" Cam said softly. For all she wanted to fight for him, she couldn't help but let her heart bleed for him a little bit, because she knew Brennan wouldn't let anything happen between them.
"At the moment, yeah she is. She's healing. But you know what? Who knows what's going to happen in the near or distant future. We have a trust thing happening, and that's what matters the most to me. I can't let us having a bit of fun on the side ruin that. Cos that's all it is to both of us Cam, just a bit of fun right?"
Cam slowly looked Seeley in eyes, knowing she had lost. She whispered, "You're right Booth. Only a bit of fun."