I'm quite enjoying this story so far. It's nice to see Harry's character using his anger in a constructive manner.
I don't think Harry has had much of a chance to work through the five stages of grief yet.
Thanks to he way he was raised, Harry had pinned his hopes for a 'happily ever after' (if such could exist for him) with Sirius as a pseudo parent. That's been ripped from him now, so I can't imagine he'd be able to cope all that well, especially on top of his fifth year.
In a way it's a real shame that his budding relationship with Luna is starting now, as it is tainted by the fact that Harry is at least partly 'broken' (emotionally) by all that he's been through, and therefore vulnerable.
Fortunately, I don't see either Luna or Harry (or Hermione for that matter) giving a damn about all that being such pure souls. :D