Well, in fanfiction, compared to the original books, Harry's role as champion can be a lot different. He may be involved in more complex political situations within Hogwarts. In the books, the focus was more on the tournament tasks, but in fanfiction, he could be dealing with power struggles among different groups of students or teachers while being the champion.
In the original books, Harry's time as the Hogwarts champion was full of danger mainly from the tournament tasks. However, in fanfiction, his role as champion can take many new directions. He could be the center of a prophecy that was not in the original story. His relationships could be re - imagined. For example, his relationship with Cedric Diggory could be explored in a different way. Maybe they become closer allies instead of rivals. Also, as a champion in fanfiction, he might have to deal with magical creatures that are not in the original tournament, leading to new and unique adventures.