A/N: Another one that I've been thinking about for a while. Big thanks to Natesmama for the beta read on it. Love you!


~Answer~

"Daddy?"

"Yeah?"

"How did Caroline get into mommy's uterus?"

Brennan, who had just stepped out of their bedroom and into the hall when she heard the question, froze. She'd been quiet so as not to wake the baby, and now struggled, torn between continuing down the hall to participate in a discussion that was certain to make Booth uncomfortable, and in satisfying her curiosity about what he would say.

It was eavesdropping, and wrong, and ...she couldn't help herself.

"What?" Booth's voice sounded strained.

"Mommy explained how Caroline got out, but how did she get in there?"

Brennan continued quietly down the hall - it wasn't creeping, she told herself, simply walking quietly so as not to wake Caroline.

Very, very quietly.

She reached the place where she could see into the kitchen, and paused, aware that neither of them had yet seen her. Booth was staring at Christine, his expression a bit desperate.

"Um, maybe you should ask mommy."

"Don't you know?"

"I, ah, yes. Yeah, I know." Right at the moment, he sounded like he regretted that fact very much. Brennan watched as rubbed his face with his hands, and then looked down at Christine, his face a study in mortification. After a moment's hesitation, he lifted her up to sit on the counter so they were face to face. "It's hard to explain, though." He paused, plainly searching for the right thing to say, and Brennan started to move toward them, to help. Then Booth huffed out a breath and said, "Girls' and boys' bodies are different."

"Baby Lance has a penis. I have a vagina."

Proud that Christine had remembered the terms, Brennan smiled, then watched as color came into Booth's face. "Yes. Yes, he does. And when they grow up, men and women...ah...put their different bodies together in a certain way, and sometimes a baby begins to grow."

Given Christine's age, he wasn't doing a bad job of explaining it, however miserable he looked, Brennan thought. Her children were truly very fortunate to have him as their father.

"So a boy with a penis could put a baby in my uterus?"

His head snapped up at that. "No! Not for a long time yet," Booth said, sounding like he was strangling. "It's something that grown-ups do, when they love each other very, very much, and want to be together for always."

"Oh. And you did it to mommy? Because you love her?"

Obviously even more uncomfortable at the personal turn of the conversation, he nodded. "That's right."

Christine cocked her head at him. Brennan couldn't see her face - only his - but she could well imagine the expression. "Is it fun?"

At that, Brennan finally took pity on him, and stepped into the room. "It is very pleasurable, Christine. But your father is right. It is much more so when you're older, and there is love." They both turned, watched as she crossed to them. But she was focused on Booth. Full of all she felt for him, she kissed him, let it linger for a moment, then leaned against him as she looked over at their daughter.

Christine had a thoughtful expression on her face. "Are you going to make another baby now?"