Rickman's best roles are when he is the smartest person in the room and has to endure the stupidity around him. He makes a hilarious comic villain.
With such a sappy theme: "Love is the most powerful magic of them all." she is not going to go off of her theme and she isn't going to make Snape untrustworthy. Dumbledore trusts him without question and without explanation. He'd never even hinted why, except in the trial scene where he stated that Snape came to the good side before Voldy was defeated.
First, a couple of early theories: The Dursleys are going to look more sympathetic and at the same time more horrific. Dumbledore hinted at something and I think it's that Dudley was offered admission to Hogwarts and they (probably Petunia) said no without telling him. But given the death and destruction in the magical world, who can blame them?
Harry will face the opportunity to use an unforgivable curse and will be conflicted. When he tries to use it, he will mean it, and it will either be against Voldy, Snape or himself.
The main theme is self-sacrifice. Harry may have to do such. Here's what I think will happen: They think the necklace was fenced by Fletcher, but it was horded by Kreature. They'll get the cup and the Ravenclaw artifact, which will be the main focus of the "mystery search" part of the book. They won't know what the sixth one is. I thought at first that it might have been Harry. That would force Harry to sacrifice himself. But now I'm not so sure. I think Naghini is a mistake by Dumbledore -- even he is not convinced. I think it's a Gryffindor artifact -- the sorting hat. The sorting hat continues to degrade its own job. It fits into the warning by Mr. Weasley in that you cannot see it's brain, even though the song in book for said that the founders "put a brain" in him. That's a strange choice of language (I would have used "mind") and sticks out.
My guess is that Snape loved Lily, she spurned him, but felt sorry for him. He lashed out at her out of frustration at his unrequited love in the flashback in book 5, but still felt it. When he heard the prophecy, it could have applied either to Harry or Neville. Neither was "marked" then. It was Snape who added something when he told Voldy to make him go after the Potters instead of the much more powerful Longbottoms. My guess is that Regulus Black was sent, but couldn't do it. It was then that he rebelled and enlisted the help of Snape -- remember the stuff in the bowl was a potion, of sorts, and I think Dumbledore was speaking as Snape when he found out that he wasn't going to be able to kill just Harry, that Voldy was going to kill Lily if he had to. Voldy discovered RAB's treachery, but not Snape's.
At that point Snape made an Unbreakable Vow to protect Harry. Snape may sacrifice himself to save Harry and finally end Voldy's rule.
Pettigrew's silver hand might be used to kill Greyback.
It will be interesting to see how Draco Malfoy is treated. Since he's redeemable, JKR will probably redeem him eventually.
But ultimately, there will be a showdown. Harry will have a disarmed Voldemort on the ground after a furious battle, Harry's wand pointed and say:
I know what you're thinking. "Did he destroy six horcruxes or only five?" Well, to tell you the truth, in all this excitement I kind of lost track myself. But being as this is a phoenix-feather wand, the most powerful device in the wizarding world, and would blow your head clean off, you've got to ask yourself a question: Do I feel lucky? Well, do ya, punk?
I loved Rickman in Galaxy Quest.....I loved that movie, too.
I thought Rickman was wonderful in "Quigley Down Under"; he had the right blend of arrogance, meanness, and even aw-shucks hero-worship to make him an intriguing villain. And gosh, he was so thin there in comparison to Snape!