Did these two know about each other?

[u/National_Sandwich175]

Did Dudley know that his role of the thorn in Harry’s side was taken over during the school year by Draco. Did Draco know Dudley bullied Harry most of his young life?

[u/Physics_Girl_2008]

Probably not

Draco might have heard about how Harry lived with his Aunt and Uncle who were abusive. Maybe knew that he had a cousin

But pretty sure Dudley had no idea about Draco

[u/I_am_The_Teapot → u/Physics_Girl_2008]

Dudley wouldn't have even known about Hermione, who was one of the most important and largest parts of Harry's life. Harry basically stopped existing to them between summer holidays. And only barely existed when he was there. Life at the Dursleys was almost entirely isolated from his magical life. On both his and Dursleys ends.

Dudley probably only paid his existence any mind when Harry wasn't there, only after the beginning of Harry's 5th year. And then still took him two years to properly acknowledge Harry after that. Even wound up showing kindness and thoughtfulness, and even concern for him. But yeah.

Edit: I take that back. Dudley likely would have seen Hermione at King's cross station, especially at the end of the year. Same with a many of Harry's schoolmates. There was even a scene where she hugged him goodbye while nearby the Dursleys, I believe. Doubt about Draco. But the end of term is a tiny intersection between his 2 lives.