as we endured

Regulus Black wanted to die, at that moment. He wanted to die, and Sirius made him live. So, he'd do his damned best to make sure the next generation lived too. AU / Regulus lives, redeems himself in the eyes of the Order, and joins the Hogwarts Staff as a therapist. If only his salary included 'helping to save Hogwarts every year since Potter arrived'.