Oh god! ♥ This was just… very, very nicely done. I love how difficult and tense things were between Alison and Peter for a long, long time, how lost and scarred they felt, how it helped to open up to one another and talk, yet it did not fix much and it didn't erase the mutual betrayals and the trauma. Still, they were progressing, little by little, and you portrayed that in a very realistic and rather moving manner. But then they had to go back… and that was just the end of everything. ♥ Of course the Master wasn't going to just leave them alone. I love Alison's distress and terror when Peter went missing, and the professor's reappearance was just perfect—not looking like he was out to punish them straight away, but proceeding with the manipulation and making sure she terribly needed him and found solace with him, before he could hurt her in all kinds of ways all over again. And the punishment came all too soon. RIP, Peter. ♥ It's truly hellish, but very well done…

And for the nitpick:
"the ease they had always felt in each other company": each other's
"he looked at me and told me it had been kinder if I had obeyed him and hit you.": it would have been kinder?
“Would it had been better for you if I had?”: would it have been
"she was certain that Peter wouldn’t have done anything than going straight to his meeting": anything else than/anything but?
"Where if Peter?": is
"You have to agree with me you both have been behaving very recklessly and rather inconsiderate.": inconsiderately?