Yes, there might be. The 'Harry Potter' and 'Hunter of Artemis' universes are both quite popular in the fanfiction world, so it's possible that someone has combined them in a fanfic. You can try searching on major fanfiction websites like FanFiction.net or Archive of Our Own.
Maybe Harry discovers he has a connection to Artemis and becomes a Hunter. He could use his magic skills along with the hunting abilities. For example, he might use magic to track down magical creatures that are also targets for the Hunters. He could face challenges from both the wizarding world, like Voldemort's followers, and the challenges within the Hunter of Artemis community, like rival Hunters or ancient curses related to the hunting.
One interesting aspect could be the unique character transformation. A female Harry Potter brings a different dynamic to the story. And as a Hunter of Artemis, she might have new powers and responsibilities. It could also introduce new relationships and conflicts within the Harry Potter universe that we haven't seen before.
One similar fanfiction could be 'Fem Harry Potter in the Magical Realms Beyond Hogwarts'. It has a similar concept of taking the female version of Harry Potter into a different and often more adventurous setting. Also, 'Fem Harry Potter: The Time - Traveler' is quite interesting. It allows her to travel through time and change things in the wizarding world, much like how being a Hunter of Artemis might change her role in the original 'Fem Harry Potter is a Hunter of Artemis Fanfiction'. Additionally, 'Fem Harry Potter and the Lost Magic' is a fanfiction that gives her access to a new kind of magic, just as she might get new abilities as a Hunter of Artemis.
A major theme is identity. Fem Harry has to figure out who she is as a hunter of Artemis while still being Harry Potter. She may struggle with how she fits into the wizarding world and the world of Artemis's hunters. Also, loyalty is often a theme. She might have to choose between her loyalty to Hogwarts and her newfound loyalty to Artemis. And there's usually a sense of adventure as she goes on various hunting - related quests.
I'm not sure if you've heard of 'Artemis's Chosen, Fem Harry'. It's a fanfiction that really dives deep into the concept. Fem Harry is chosen by Artemis for a special mission. The story is full of action - packed scenes where she uses her hunting skills and magic to overcome various obstacles. It also has some really cool descriptions of the places she visits, whether it's the Forbidden Forest in Hogwarts or the mysterious hunting grounds in Artemis's world.
First, understand the rules and lore of both universes thoroughly. For Hunter x Hunter, know about nen, the different types of hunters, etc. For Harry Potter, understand magic, Hogwarts houses, etc. Then, come up with an interesting premise that combines elements from both. For example, a character from Hunter x Hunter discovers they have magic like in Harry Potter. Keep the characters' personalities true to their original selves and let the plot develop organically as the two worlds collide.
There's also 'Hunters at Hogwarts'. In this fanfiction, the Hunters end up at Hogwarts for some reason, perhaps a strange nen - based portal. The cultural clash between the two groups of characters is really fun to read about, and the author weaves in elements from both series seamlessly, making for a really engaging read.
Another way is through a friendly rivalry. Artemis, with his brilliant mind, could compete with Hermione or other intelligent characters in the Harry Potter world in areas like spell - making or magical theory. They could learn from each other's different ways of thinking, with Artemis bringing in scientific thinking and the Hogwarts students sharing their magical knowledge.
One great fanfiction in this concept could be 'The Artemis - Potter Connection'. It beautifully weaves the story of Harry Potter being Artemis's daughter. The author creates a unique world where the magic of Hogwarts and the wild, free spirit associated with Artemis blend well. The protagonist shows traits of both Harry Potter's courage and Artemis's independence.