Sure, Cedric Diggory probably isn’t a character you think of that often but, throughout the Harry Potter series, he became more and more important so let’s look at that.
It didn’t seem like Cedric Diggory was going to play that big of a part in the Harry Potter series as a whole but then, as we went on (and saw Harry Potter and the Cursed Child), it became clear that his importance to Harry and his story was greater than we could have imagined. First, it comes from Harry watching his new friend die.
Cedric is the kind of character who many quickly write off. Just a character who serves his purpose in Harry Potter and the Goblet of Fire and that’s that. But he’s more than that, he serves as a moral compass for Harry in a way.
When Cedric Diggory died, Harry was then in a mindset that it was all down to him and his fault. In no way was Harry the reasoning behind it but he was forced into that idea because of everyone reacting to the situation.
And then, with Harry Potter and the Cursed Child, Cedric became even more important because yet again, Harry was faced with the guilt of his death. It’s strange but since his introduction to this series, Cedric has made a name for himself in the sense that he was always in Harry’s life, even after his death, and it is weirdly important for fans to look at him as a character and how much he impacted the entire series as a whole.