The Doctor couldn't decide whether or not he was surprised. This had always been how it ended; the Master would come so very close to killing him, and then he would let him go. But this time had seemed to be different, he seemed like he really was going to kill him - and he still wasn't sure if that gun had been purposely left empty - but here he was, free to go.

Get out while I still have the sanity to realize you're much better off alive than dead. Still gripping onto the doorframe, he rolled that over in his mind. The Master, he realised, had been wrong about the destruction of Koschei, of any kind of conscience. He looked away as anger welled up in him again, flinching at the sudden psychic contact as though he thought it another attack. But instead it was the way out.

He said no words, just gave the corner the Master was in one last glance before he pushed himself painfully out the door and into the corridor. No more time to focus on thinking about the Master's actions. He was becoming dizzy, and he needed out. And so he went, leaning on the wall at times for support, hoping like hell that he wouldn't pass out before he got there.

He wasn't going to thank him.