A/N There isn't much of a story here, just a bit of interaction between Sherlock and the Doctor.

"People are dying, Sherlock!"

"I've told you, sacrifices have to be made!"

"Sacrifices! These are human lives, humans, wonderful, brilliant human beings we're talking about! Human beings like you!"

"There isn't a human alive who is like me."

The Doctor put his head in his hands in exasperation, "These people have families, homes, friends, lovers. You can't treat humans like pawns in a chess game. Sherlock, you know I love having you around, I admire that you can keep up with me when I go off on a tangent. I thought I'd keep you around for years, that you'd be an equal. But there's a reason I chose human companions. They feel. They keep me in line, they stop me going too far. If you can't do that, if you treat humans like playing pieces then there's no room for you on my TARDIS. If you do that, then you can consider me your opponent." The Doctor lifted his head, his sorrow hid behind a stern, solid look, a look that said he meant it.

Sherlock fell backwards onto a chair and put his own head in his hands. He bit his lip, considering for a moment what a wonderful challenge the Doctor could provide him with. What a wonderful game of chess this could be. But he respected the Doctor, had come to appreciate that he was possibly the only person who could keep up with him. His opinion mattered.

"Fine," Sherlock said, "If they're that important to you then we can keep them alive."

The Doctor nodded, a worried look still on his face. "They should be important to you Sherlock. They should be important to you too."

"We could all die if we don't sacrifice them. We will never catch the man behind this."

The Doctor shrugged. "Well, what's life without a little risk."

Sherlock held back a tiny smile, at least his time in the TARDIS might not be boring.

The Doctor span, a cheerful façade plastered on his face as he pressed buttons.

Inside, he was worried, but also determined that before he dropped him off home, Sherlock would learn to become truly human. None of this Sociopath rubbish, he know Sherlock was capable of feeling, and he'd make sure Sherlock knew it too.