Professor McGonagall's Office
Though no one ever really thought of me as the kind of teacher you could go to without judgement, I seemed to spend an awful lot of time with students in my office – sometimes crying, but a lot of the time in trouble. There were the obvious candidates, of course – James Potter and Sirius Black, for example – but every so often other people would just wander into my office and I would spend the evening becoming more and more stressed.
In fact, thinking about it, it was the ones that I didn't expect that caused the most stress, for the most part because the reason they were in there was so completely and utterly bizarre.