In the years following the war the Ministry of Magic struggled to regain the public's trust whilst people struggled to find peace of mind in the uncertainty of Voldemort's disappearance. In 1985 letters start appearing with a very concerning or very hopeful kind of message, depending on your point of view and personal beliefs. They are so anti-establishment, in parts so truthful, and thus potentially dangerous that the Ministry controlled Daily Prophet won't publish them or any talk about them on the Readers' Column.
The letters lay out a vision of future where the Ministry no longer exists and most wizardkind have lost their magical powers, leaving only a select few to rule and carry on the magical bloodlines. A world where muggle-borns and squibs are all treated the same as half-bloods and purebloods. A world where magic is kept secret from muggles but is not thought of as something that makes one superior, and where people like Grindelwald and Voldemort can never rise again.
The authors call themselves the Children of Merlin. They are a secret society seeking total revolution, to rebuild the world in their image of true equality. They are recruiting new members from like-minded people, both muggle and wizardkind. They say they will not go to war over this but claim they have a nearly perfected peaceful weapon to make it happen, to take magic away from those they deem unworthy.
Will your character be drawn to join them from genuine agreement or fear? Or will they judge their vision or their method of achieving it as too radical for support and try to fight it instead? Or will they try to keep calm and living their lives, putting their faith in the Ministry after it finally takes action when a threat is made against Hogwarts and it seems to have been for real.
This is a character driven rpg where we explore the 1980s era of relative peace up to Voldemort's reappearance, and not everything has to be about or revolve around the main plot. No wizardkind person can completely ignore what's going on but your character can be as much or as little involved in the plot as you want and still have plenty to do.
By the end of the decade the revolution has been prevented, but what part did your character play in it---if any? Do they have regrets? Will they wish it had turned out differently when in the summer of 1992 rumours spread that He-Who-Must-Not-Be-Named has resurfaced?