Harry's parents are alive.. the left Dodge when the tough got going.. (leaving Harry and Sirius to suffer.. ) return to find Harry married To Severus.. and Sirius is alive or not. Albus is too as well .. :D
Harry is sent to Azkaban... they find him innocent.. Severus whisks him away... Love ensues!
Ginny tries a love/soulmate spell on Harry and instead of her.. it bond's Harry to Severus..