If everyone abandons Harry fanfic, it would likely lead to a significant decrease in the production of new works related to it. Fanfic authors might shift their focus to other fandoms. Also, the online communities centered around Harry fanfic would become less active, with fewer discussions and exchanges of ideas.
It could be due to the saturation of the market. There might be so much Harry fanfic already that it's hard for new works to stand out. Additionally, changes in the way people consume media, such as a shift towards more visual content like streaming shows, could also lead to a decrease in interest in reading Harry fanfic.
Some might be angry, thinking he's abandoning his responsibilities. The Ministry of Magic might try to persuade him to come back or even use force if they thought it was necessary for the safety of the wizarding world. His friends, on the other hand, would likely be sad and try to understand his reasons. They might also try to convince him to return, as they know how much he means to the fight against evil in the wizarding world.
Well, it could be a fanfic where the author bashes all the characters in Harry Potter. Maybe they don't like the way the original characters were developed or they just want to create a really dark and critical take on the whole Harry Potter universe. It might involve making the characters look bad, stupid or evil in some way that's different from the original books.
Obviously, Harry Potter would be the main character. He is the one doing the saving. Ron Weasley and Hermione Granger are also likely to be main characters as they are Harry's closest friends and often by his side in his adventures. Dumbledore might also play an important role, even if he's dead in the original story, his influence could still be there guiding Harry. And of course, there would probably be villains, perhaps Voldemort or some new dark wizard created for this fanfic.
It depends on what you consider 'good'. Some people might enjoy a fanfic that completely turns the original story on its head and bashes all the characters if they like that sort of edgy, subversive storytelling. But many die - hard Harry Potter fans would probably be turned off by it as it goes against their love for the characters. So, in a sense, whether it's 'good' is subjective.
In a 'harry saves everyone fanfic', one key plot point could be Harry discovering a new, hidden power within himself. This power might be the key to saving everyone. He could also form new alliances with unlikely characters. For example, he might team up with some Slytherins who have a change of heart. Another aspect could be that the situation is extremely dire, like the whole wizarding world is on the verge of destruction. Harry then has to go on a quest to find ancient magic or artifacts that can turn the tide and save all the wizards and witches from harm.
It could mean that in the context of Harry Potter fanfiction, the characters or the overall allure of the fan - created stories is so appealing that it's like everyone is attracted to it in a sense. Here 'gay' might be used in a more modern, inclusive sense of just being really into it rather than strictly in a sexual orientation context.
Perhaps he is trying to hide his true self. He may have a side of him that he doesn't want others to discover, like some special abilities or a different origin. So, being cold to everyone helps him keep his secrets and avoid getting too close to people who might figure him out.