Well, it would be really strange. Harry Potter's world is full of magic with its own set of rules, like Hogwarts, wands, and spells. Slenderman, on the other hand, is a very different and often creepy entity. In such a fanfiction, Harry might grow up with a much darker and more mysterious upbringing. His values and understanding of magic could be warped. Maybe he'd be more isolated as Slenderman doesn't seem the type to encourage socializing. He could also have some really unique powers that combine the wizarding world's magic with whatever influence Slenderman has.
In such a fanfiction, Harry might grow up with a very different set of values. Slenderman is often depicted as a creepy and somewhat malevolent figure. So Harry could be isolated from normal society. He might be trained in skills that are not typical for a regular upbringing, like how to move stealthily or sense danger in an uncanny way.
The biggest difference would be in Harry's upbringing. In the original, he was raised by the Dursleys which was bad but still in a relatively normal (albeit cruel) Muggle environment. With Slenderman, it would be a completely abnormal and often terrifying experience. His understanding of good and evil would be skewed. Also, the magic he'd learn and how he'd use it would be different. In the original, magic was mainly for positive things like protecting and helping others. Here, it could be used for more menacing or self - serving purposes.
There's a fanfic called 'Slenderman's Shadow over Hogwarts'. In this story, Slenderman's influence starts to seep into Hogwarts, causing strange happenings. The author does a great job of portraying how the students and teachers react to this new and terrifying threat. It's full of suspense and keeps you on the edge of your seat.
One main theme is the clash of different fictional worlds. Harry Potter's world is full of magic, spells, and a well - established structure, while Slenderman brings a sense of horror and the unknown. So, the theme of how these two different elements interact is quite prominent.
Well, it could be really strange. Harry might use his magic against Slenderman. Maybe he'd try to protect the other characters in the Slenderman world with spells like Stupefy or Protego. It would be a wild mix of two very different fictional universes.
A 'harry potter is slenderman fanfiction' might be a very dark and twisted take on the Harry Potter universe. Imagine Slenderman being some kind of new dark force that Voldemort was trying to control or was in cahoots with. Harry would then have to face not only the Death Eaters but also this strange, otherworldly horror. The magic in the story would have to be re - imagined to deal with Slenderman's abilities, like his teleportation and mind - affecting powers. However, it would be a difficult balance to keep the essence of Harry Potter while introducing such a different horror element.
It's not extremely common. While there are many crossovers in fanfiction, combining Harry Potter with the rather dark and disturbing Slenderman concept might not appeal to the mainstream Harry Potter fanfiction audience. However, there is a niche group that enjoys such out - of - the - box crossovers for their unique take on familiar characters and worlds.