Hogwarts : Slytherin！

This is a story that takes place in the same era as the original 'Harry Potter' series.
However, its protagonist is not the famous Harry Potter, but rather a poor illegitimate child from another mysterious magical family, William Whistler.
William Whistler is also a child who survived the Avada Kedavra curse, although at the time he was still in his mother's womb - well, actually, the fetus and his mother had both died. The survivor was a modern person who traveled back in time to the fetus and knew all the original plots of 'Harry Potter.'
He is reborn in the wizarding world, experiencing those well-known stories from a completely new perspective and altering their plots.
This means that the story will have a broader, more mysterious, and more detailed worldview (at least the author will try their best to achieve this).
Alright, let the story begin with our William Whistler catching the train to Hogwarts...