Yes. In the Harry Potter fandom, the concept of Harry being a Horcrux is quite a popular and fascinating one for fanfic writers. It adds a whole new layer of complexity to the story and character relationships.
In fanfic, it could be through a dark spell gone wrong. Maybe a spell that was meant to destroy the Horcrux instead backfired and caused it to merge with Harry.
In a 'harry potter and the last horcrux fanfic', it may center around the significance of the last Horcrux. It could depict the emotional and mental state of Harry as he approaches the end of his long journey. There could be unexpected twists, like the Horcrux being hidden in a place no one suspected. It might also expand on the lore of Horcruxes, for example, by showing different ways to detect or destroy them that were not mentioned in the original series.
One interesting 'horcrux harry fanfic' story could be about Harry finding a way to destroy all the horcruxes in a completely new and unexpected manner. Maybe he discovers a hidden spell that can disintegrate the horcruxes without the use of the sword of Gryffindor or the basilisk fang. Another could be a story where Harry becomes a horcrux in a different way than in the original series, and how he has to deal with the implications of that. It could involve him having to face Voldemort in a more complex psychological battle.
Well, identity exploration is a big one. Harry has to figure out what it means to be a Horcrux on top of being the Boy Who Lived. There is also the theme of moral conflict. He is part of Voldemort's dark creation, yet he is the symbol of hope. How does he balance this? Another common theme is the exploration of magic. Since he is a Horcrux, there could be new and different magical aspects to his being that fanfic writers can explore, like how his Horcrux - ness affects his magical abilities or his connection to other magical objects.
If Harry were to create a Horcrux in fanfiction, it would likely lead to a great corruption of his soul. Horcruxes are dark magic, and the act goes against all that Harry stands for in the original series. He might start to show signs of increased aggression, a detachment from his friends, and a growing attraction to the Dark Arts.
In some fanfics, if a Horcrux were to merge with Harry, it could potentially give him some of Voldemort's powers. But it would also likely be a great struggle for Harry's soul. He might have to constantly fight the dark influence within him.
Harry Potter would surely be one of the main characters. Since it's about the last Horcrux, he's the one on the mission to destroy it. His friends, like Hermione and Ron, would likely also be main characters as they usually accompany Harry on his adventures.
Some Harry Potter - themed forums might be a good place to look for 'horcrux harry fanfic'. There, fans often share their own written works or recommend good fanfics they've read. Reddit also has some Harry Potter - related subreddits where people discuss and share fanfiction. Just make sure to check the rules of the forum or subreddit before posting or asking for specific fanfics.
A really creative concept in some 'Harry Potter Horcrux fanfic' is the idea of a Horcrux being able to change form. So instead of always being a physical object like a locket or a diary, it can transform into a living being or an intangible force. This adds a whole new layer of complexity to the hunt for Horcruxes and how to destroy them. In some fanfics, this transformation ability is related to the emotions or the intentions of the person who created the Horcrux.