This is for 16+ only
Fifty years later after the events of cursed child...
A tall robed figure arrived out of nowhere and knocked on the door of Number 12, Grimmauld place, his heart heavy.
The boy had stopped him for the last time. He had no more Horcruxes, he only had skill. After he killed them, he would look for his followers.
He would make sure they would pay the price before persuading their children to help him.
The door opened. An old woman with red hair opened the door. She fumbled for a wand but it was too late, Ginny Weasley fell down, her body lifeless. Harry ran to the door, only to see him.
"Potter," he said, his wand hand trembling, "You have thwarted my plans again and again. This time you shall pay the price and you will be sorry."
His killing curse hit Harry in the chest and he gave a cold laugh, the boy was finally dead!
He then heard the painting on the side run, it was one of the Black's. He would report this is Silvia McGonagall for sure. The half-blood brat of Minerva.
The three children ran and sent their curses at him. He defied them, yelling killing curses at them. Glass shattered, bodies fell.
Only one grandchild stumbled upon them and looked at the bodies. She had red hair and almond shaped eyes, shining an emerald green. She was no older than thirteen.
"Ava Potter, come. Join me in my regimen. You will have everything you ever wanted. Decline, and death will greet you."
Ava gave a wicked smile, "Of course."