You did such a great job with this! I've always loved 'what if' scenarios (my very first fic I ever wrote was a Snarry 'what if', but certainly nothing compared to yours!!!)
This just grabbed me and reeled me in. I love the different scenarios you came up with and how at first they seemed like better alternatives to Severus' real life, only to turn out so horribly bad.
But then in the end, everything that he lived through paid of with something good, if only he chose it, and the way you slowly developed his desire (and the reader's desire FOR him) to have that possible life, to the point he is desperately screaming 'to go back' for it - it just gave me chills.
Wonderful story, wonderful use of prompts - a perfect example of what a Snarry story should be.