I'm not sure I believe that the war would have changed his attitude that much--at least, I can see no evidence for that. I think it's more this feeling left out that you mention that could explain it. The most remarkable thing about Sirius in OotP is, IMO, the sense of futility. As if he doesn't have a purpose any more. In GoF, he had Harry to protect, and he could feel that he was doing something, but in OotP he was a prisoner of Grimmauld. (Damn you, Dumbledore.)
Sirius seems the kind of person who's got to be able to do something. Remember Snape's Pensieve? James started to torment Snape because Sirius was bored. I don't think something as sedentary and unexiting as reading would satisfy his need to do something, so anything he could do inside Grimmauld would be inadequate.
So yeah, frustration and the feeling of uselessness are the keys, I think, which is why Snape's taunts of cowardice probably infuriated him so much.
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timeasmymeasure
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Date: 2007-02-03 11:14 pm (UTC)Sirius seems the kind of person who's got to be able to do something. Remember Snape's Pensieve? James started to torment Snape because Sirius was bored. I don't think something as sedentary and unexiting as reading would satisfy his need to do something, so anything he could do inside Grimmauld would be inadequate.
So yeah, frustration and the feeling of uselessness are the keys, I think, which is why Snape's taunts of cowardice probably infuriated him so much.