Severus Snape and the Next Great Adventure (смешанная)

To rebalance a world spinning toward disaster, Lady Magic recruits an unlikely and understandably reluctant champion- the failed, thoroughly unmourned, recently departed Severus Snape, allowing him to return back to life in his fifth year, before his pivotal “Mudblood moment” as a fully repentant, far wiser, less angry version of his former young self. Snape has a Herculean task ahead. Can he fix himself enough to unite the magical world and revive a dying planet?
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Slight AU of canon- two pivotal events are different:
1)Lily and James really are flirting in the scene where Snape is hanging upside-down.
2)Snape dies in the Shrieking Shack before he can give his memories to Harry, so Harry never walks to his death a willing sacrifice and dies trying his best to take Voldemort with him. He fails to do so. Harry did collect all the 3 Hallows and is still Master of Death, though. He and Lady Magic convince Death to send Snape back to 1976 to right what went wrong.
The rest of the changes are through Snape's (and sometimes Harry's or others) actions as this story diverges very quickly from canon.