Severus Snape and Harry Potter slash fanfiction: How do they change in these stories compared to the original books?
Well, in slash fanfiction, Snape can be portrayed as less bitter. He may let go of some of his grudges more easily. Harry might grow up faster in these stories, in terms of emotional maturity. He could be more accepting of Snape's past actions. In the original books, their relationship is mostly adversarial, but in fanfiction, they can develop a friendship or something more intimate. They may also work together more closely against the dark forces, sharing secrets and strategies that they didn't in the original plot.
In the fanfiction world, Snape is sometimes depicted as being more involved in Harry's life in a positive way. Instead of just being a source of fear or annoyance in Harry's Hogwarts days as in the books, he could be a guiding figure. Harry could also change in that he might be more proactive in seeking Snape's help or advice. Their relationship could evolve into a mutual respect and even a form of love that was completely absent in the original books. This change can be due to different plot twists in the fanfiction, like different interpretations of prophecies or new magical elements introduced.