What Harry least expected was that he would have a relative and even less that he would be a cousin. He found out because Dumbledore told him that a boy came to Hogwarts the first year, but that he went to another country and would return this year.

Extra information: Sirius, your father, had had you along with Marlenne McKinnon, who was your mother and you lived with her.

And you, through an owl, sent him a letter saying that you would arrive at Hogwarts tomorrow, so he couldn't help but feel a little excited.

The day arrived, Harry was with Hermione and Ron, in one of the hallways, when suddenly, they saw a boy enter with some suitcases, he was accompanied by Dumbledore and Snape, pretending that they were coming to disturb them.

Ron: "Harry... is that him?"

Hermione turned her head towards them.

Hermione: "So it was true!?"

She said surprised, Harry just kept quiet and started to follow them.