The reason Clay was hurt in the fanfiction could vary. It might be because of a betrayal, a risky adventure, or even a random accident. It all depends on the imagination of the writer creating the story.
Maybe Clay's suicidal thoughts in the fanfiction stem from a build-up of stress, internal conflicts, or feeling hopeless about a particular situation. Different authors might have their own creative explanations for this.
I think it's because fans love the show and want to create their own scenarios involving Clay and Sheri. It gives them a way to keep the story alive and explore new possibilities within the 13 Reasons Why universe.
Maybe it's a way for the author to show the depth of Clay's internal struggles and psychological turmoil. Or it could be a reaction to specific events or relationships in the story.