He may feel a bit weird. Fanfiction can be so different from his real self. He might not like some of the wild ideas people have about him.
He might be a mix of flattered and bewildered. Flattered because people care enough to write about him, but bewildered by some of the wild ideas in the fanfiction.
Steven would probably be really intrigued at first. He's used to his own story as he lives it, but seeing different interpretations in fanfiction would be like looking at his life from new angles. He might find some of the ideas really inspiring, like if a fanfiction gives him a new way to think about his powers or his relationships with the Gems. However, he could also be a bit cautious. After all, not all fanfictions might portray him in a positive light, and he'd have to deal with that too. Overall, it would be a complex experience for him.
He feels extremely frightened.
Well, in many such fanfictions, Harry might be shocked at first. He probably feels a sense of pity for Draco too. After all, being under the Imperius Curse means Draco has no control over his actions.
He may feel a bit strange at first. It's like looking at a distorted mirror of his own life.
Batman may be slightly annoyed. He's a very private and serious person. The idea of people writing fictional stories about a character like Slade, especially if they were inaccurate or glorifying Slade in some way, could irk him. He might think it was a waste of people's time when they could be focusing on more important real - world issues.
Tom Ripley has a complex self-perception. Sometimes he's confident and sees himself as smart and capable, but at other times, he's filled with self-doubt and insecurity.
Harry is likely to be shocked at first. He has always seen Draco as a self - willed rival, so finding out that Draco is being controlled by the Imperious Curse completely changes his perception. He might freeze for a moment, trying to process what he has just realized.
Vernon could be quite curious. He'll be eager to read what others have come up with. There might be new ideas, different takes on his character or his world that he hadn't thought of before. So he's probably excited to explore these new interpretations.
She probably feels excited. Discovering the tooth fairy is like finding out about a wonderful secret world. It's something new and magical, so she would be filled with anticipation and joy.