The Price of Magic (слэш)

Haunted by the ghost of a former student, an ex-wizard struggles to preserve magical knowledge for future generations.
When Harry Potter died, twin wands' explosion wiped Europe clean of magic. Enchantment-free, Gringotts crumbled into a mass grave for goblin bodies. Pixie corpses covered the meadows. Romanians buried their last dragon.
Wizards remained. Thousands flooded Muggle streets with useless chanting, unable to return home through non-existent wards.
They had nothing except pride. Remember that when watching a middle-aged, redheaded waitress and her daughter taunted by children for their strange way of talking, passing the sallow-faced, somber neighbour who prefers candles to electricity, finding a sky-blue twinkle under matted hair of a homeless man.
Pride was the reason they survived.