A Visitor from Another World in HP

During a mission, the interstellar guardian Lacker suffered severe damage to his mental powers. His friend, Dr. Octavia, a base scientist, sent him to another world to recuperate. An energy disturbance caused by the explosion of blue energy crystals disrupted the transport device. By a twist of fate, Lacker didn't enter his intended body. Instead, he awoke inside Voldemort, who was in the middle of splitting his soul to create a Horcrux.

In 1980, the British wizarding world was shrouded in the shadow of Voldemort and the Death Eaters. Having split his soul too many times, the Dark Lord had become volatile and paranoid, his face twisted out of shape. He kept the entire wizarding world in fear and even left the Death Eaters in a state of panic. Lacker's arrival briefly brought this atmosphere of terror to an end.

But then Peter Pettigrew's betrayal, and his friend's actions at Dumbledore's urging, led Lacker to Godric's Hollow after all. There, he entered his intended body once again: Ise Potter.

Because of the Death Eaters' attack, Ise Potter, who had been frail from birth, was kept under protection in the home of Abbey Megan, a retired St. Mungo's healer. After the Dark Lord fell, Hagrid was ordered to take Harry Potter to Dumbledore, while Sirius decided to bring Ise back to St. Mungo's. An accident along the way led to Sirius's capture, and Ise disappeared without a trace...

Knowing nothing about his identity, Lacker grew up in a Muggle orphanage until he was seven. After saving Isabella Kyle in an accident, he was adopted by the Merson family at ten, becoming Lacker Merson. At eleven, he entered Hogwarts School of Witchcraft and Wizardry...

Theme: The butterfly effect