Much of what Harry says about Malfoy, obviously, but also Hermione's comments on Malfoy, the way Harry is proven wrong (and hence Hermione right) on "how many girls have been princes?", and so on. Oh, and Ron's comment about how it doesn't matter what Dark stuff is smuggled out turns out to be a prediction for the end of that very same chapter.

Trelawney's rambling seems like it should mean something - the "that can't be right" only makes that more likely - but it seems too vague to be very helpful. Unless we figure out who "the questioner" is... Dumbledore? Making the "dark young man" Malfoy? It's a bit of a stretch.