Jack stopped at the door and tried to smile at the Doctor, but he didn't really have the energy for it. "I will," he said with a nod.

He took a long breath and stepped inside, a hand on the handrail for support (which luckily this time didn't burn or freeze, or if it did he didn't recognise it).

"I think..." he started, "I think though maybe this is one I have to do alone. I need to put things right. I owe her that, if nothing else. I'm not going to make the same mistakes again."

Taking the extra steps forward he looked up and around the TARDIS. He didn't want to leave. Not one bit, and his heart clenched tight at the thought of it.

"So," he sighed, "back to London, I guess."