I think that it's interesting to point out the following little tidbit. When Harry realizes that Bellatrix did in fact cause Sirius to fall through the veil and that Sirius is dead he says the following...
"SHE KILLED SIRIUS! SHE KILLED HIM--I'LL KILL HER!"
Then when he gets a chance he does "Crucio" not the killing curse.
And Voldemort made Harry think that he had kidnapped him, which is the reason the kids ended up in the MoM anyway. And Sirius came to save Harry. So it's partially Voldemort's and Harry's fault Sirius was there too.
He did decide to hurt her and not kill her. I had forgotten that. It does say a lot about Harry's character. I also agree with Tiger that a Series of events led to Sirius' "death".
ohhh i love those books.. the movie for the first one is coming out soon.. sorry off topic i know but i saw the words " a series of unfortunate events"
Won't you go away
and leave me till the time of dying days
stand here by my side
and watch the river flood and pass us by