I have always found it heartbreaking that Blaine went to a party where he didn’t know anyone except for the guy he came with, and proceeded to get absolutely shit-faced. I think it says a lot about his character that he was that reckless with himself and his body, and apparently gave no thought as to how he would get home afterwards (I think that if they had discussed it beforehand Kurt would have let Burt know that he would possibly have a friend staying over). Looking at this behavior, it makes his specific-sounding example he gave to Burt during Sexy about the danger of Kurt going to a party and getting drunk and being taken advantage of, seem like it came from a personal place. We don’t know much about Blaine’s life before Kurt meets him, but Blaine was lucky that with the New Directions he was among people who were not going to force or coerce him in to anything; but if he had been among seedier characters there would have been potential for things to go bad very quickly for him.
I still get sad feelings about this.