vega-ofthe-lyre:

“Doctor, we can’t just leave him there!”
“Keep him in your mind. Don’t forget him. If you forget him, you’ll lose him forever.”
“No, wait, on the Byzantium, I still remember the clerics because I am a time traveller, now, you said -“
“They weren’t part of your world, this is different, this is your own history changing.”
“Tell me it’s going to be okay, you have to make it okay!”

Cold Blood; Doctor Who 5.09.