I absolutely loved this. I haven't had time to read any snarry games fics so far and you hav broken my duck, what a wonderful way to do it. I didn't read the prompt so I had no idea what was going to happen when Severus turned out to be a Severus from another reality, a wonderful twist that really knocked me for six!
Your Severus was so delightfully nasty to Harry, until he finally started to fall in love with him. I loved the background characters too, everyone from Narcissa to Paracelsus.