Harry Potter might react with a mix of fascination and disbelief. On one hand, he would be drawn into the imaginative scenarios presented in the multiverse fanfiction. He might be excited to explore the different possibilities of his life and the lives of those around him. For instance, seeing a universe where Hagrid is a powerful wizard instead of a gamekeeper. On the other hand, some of the more outlandish ideas in the fanfiction might make him skeptical at first. But overall, he would likely be very interested in this new way of looking at his world and the magic within it.
He might be really excited. Naruto loves new and exciting things, and the multiverse fanfiction would be full of that.
He'd probably be shocked. His world is already full of surprises like different jutsus and powerful enemies, but the multiverse would be on a whole new level. He might not believe it at first and think it's some kind of elaborate prank or illusion.
He'd probably be very curious. Harry has always been interested in new things, and this would be a whole new type of story for him.
Harry would be quite surprised at first. He'd be thrown into a world without magic, yet full of strong emotions and drama. He might feel a bit out of place, but as he gets into the story, he'd start to understand the human nature in it. He could admire the courage of the characters, like how they faced the disaster. And he might also be a bit confused by some of the muggle concepts like the class system on the ship.
He might be shocked. The fanfiction could show his friends or himself in situations that are completely different from what he knows. For instance, if it shows him losing to a minor villain, it would be very unexpected for him.
Harry might react with a sense of both curiosity and discomfort. The fanfic might have elements that are completely foreign to his understanding of his own story, yet he could also be intrigued by the creativity of it. He might start to wonder how much of his own life has been turned into something so different in the minds of others. He could also feel a bit protective of his own story and those of his friends, not wanting it to be misrepresented too much in the fanfic.
The fandom's reaction would be quite mixed. Some fans, who are more open to extreme and creative interpretations in fanfiction, might find it an interesting and bold take. However, the majority would probably be horrified. Snape is a beloved and complex character, and this idea of him being aroused by Harry fanfiction is so far from what J.K. Rowling created. It could lead to a big debate within the fandom about the limits of fan - created content and how it should respect the original source material.
He might be very surprised. The magical concepts are so different.
It broadens the perspective. By seeing different versions of the wizarding world in the multiverse, readers can understand that the original series is just one of many possibilities. For example, in the multiverse, the Hogwarts houses could have different characteristics or the wizarding world could have different political systems.
There's a chance he'd be inspired. The stories of the Naruto characters' determination and growth in the fanfiction could stir something in him. He might think about his own journey as a wizard and how he can further develop his skills and character, taking cues from the Naruto characters' tenacity.