Yes, there are some out there. Some fanfictions explore this alternate relationship in really interesting ways. They might rewrite key scenes from the original series with this new family dynamic in mind. For example, Snape's interactions with Harry could be completely different, filled with a fatherly protectiveness that was hidden before. However, not all fans of the original series like this concept as it goes against the canon, but it does open up new and exciting storylines for those who enjoy exploring different possibilities.
There are definitely some. In these fanfictions, the story often delves into how Snape would have raised Harry if he knew he was his father. It could involve Snape teaching Harry more about the dark arts in a more controlled and positive way. Also, the relationship between Snape and Lily could be re - examined, perhaps showing a more complex and loving connection that led to Harry's birth. But it's important to note that this is all in the realm of fan - created content and not part of the official 'Harry Potter' story.