I really, really hope that Sirius makes a return but I don't think it will happen. JKR has said on numerous occasions that he is truly dead, he is no more, he is an ex Marauder

. The mirror Harry had bugged me at first but having re-read that bit I have now discounted it. When Harry throws it back in his trunk it shatters and I think that is the last we will hear about this.
Remember Fudge calling him Voldemort's most loyal follower and that Sirius went mad
I actually don't think Sirius was ever an undercover Death Eater (no I am saying this very quietly

). I think the comments about him being Voldemort's loyal servant all sprang from the false conviction and Peters betrayal. I did find something else semi interesting though.
I had assumed the whole horcrux thing was a secret, that Dumbledore had only really discovered what he was up to in HBP (maybe a little earlier) and certainly not when he was in power before. However in the graveyard at the end of GOF, Voldemort implies that all of the Death Eaters were fully aware of what steps he had taken to cheat death. Now this would mean that Snape knew and explain how Regulus knew to go for the locket. So three possibilities/questions
1. If Dumbledore knew Voldemort had bits of his soul scattered near and far which could bring him back to life why did he wait so long to track them down? Wouldn't it have made more sense to get them before Voldemort got his powers back.
2. Again if Dumbledore knew, why didn't he tell the Ministry that Voldemort could and would come back - at that time they were bound to have believed him
3. Or if none of the above is true why didn't Snape tell Dumbledore about the horcrux

. Oh I hate this, I am finding more and more reasons to doubt Snape
