"I'm sorry, John. Really, I am. I can't help that the TARDIS decided to bring you here. Maybe she had a reason. Maybe she didn't. There's no way of knowing, not really." The Doctor tried to look at the problem from John's perspective, tried to understand how he must feel. He supposed it might be a little like living with a death sentence constantly over your head.
"If it helps ... you're not the only one who finds the idea of being here more than a little disturbing. We all have lives we want to go back to, and some of us are learning things by being here that we never wanted to know."