Repeat the Past - Part I

Severus Snape wanted a second chance; Severus Snape got a second chance, to make a difference to a different future. It was not quite what he expected, but it will change the fortunes of both him and Albus Dumbledore - throughout their lives, for good. AD and SS, father-son, a different take, for me, on both characters...but not quite perhaps in the way you are expecting...