There were some things that were mentioned in book 5 that I wonder if they won't be significant in later books. For instance, the family tree that Sirius shows Harry that all the pure-bloods are related (of course, that did come back a little later when we learned Kreacher went to join the Malfoys and when we meet up with Bellatrix later). Or how about Mrs. Weasley fighting the boggart and seeing all her children dead...will a Weasley be lost in either book 6 or 7?
And what about the veil that Sirius disappeared through that Harry and Luna talked about...will Harry (and possibly Luna) go back to the Department of Mysteries to talk to people on 'the other side'? I wonder, now that Harry has gotten an insight into Snape, if he and Snape won't eventually talk...I'm not sure. Maybe they never will, but I think Harry will continue to learn about his parents and their past.
Can you think of anything else that might be foreshadowing for future books and what might happen? There were loads of details in book 5 and all sorts of things that could have been foreshadowing or laying the foundation for future books. Harry has lost all his 'family' now and has realized Dumbledore isn't perfect...it'll certainly make him feel isolated...which makes me think he'll think over what Luna said about the veil and want to try to talk to Sirius. It'll be interesting to hear your ideas about foreshadowed events and clues in book 5 about things to come.
~ Lizzy


