Wormwood and Asphodel

Severus Snape finds himself alive when he shouldn't be, and much to his dismay back inside his teenage self. No idea how he had managed the impossible feat he is determined to turn the tide of war before Voldemort ever has the chance to try and target Lily. What he does not expect is that Remus Lupin is in the same boat as him [rated m for strong language, mentions of child abuse]