Cadmus is a part of the rich tapestry of Greek mythology. It's not a real historical person or event. Myths like these often contain symbolic and imaginative elements, making them fictional creations.
Another possibility is that Cadmus is a character who has a connection to a prophecy related to Harry. Maybe he is the one who discovers the prophecy or has some knowledge about it that he shares with Harry at a crucial moment. This could set off a chain of events that changes the course of Harry's battle against Voldemort in the fanfiction.
Well, without actually reading it, it could be a fan - made story that combines elements from the Naruto universe with something related to Project Cadmus. Maybe it features Naruto characters in a situation inspired by the concepts or events from Project Cadmus.
There might be a fanfiction where Cadmus plays a key role in a plot against Voldemort. He could be secretly gathering information or creating powerful spells to aid Harry and his friends. In this type of fanfiction, Cadmus' character might be portrayed as a sort of underground hero within the wizarding world, with his own motives and goals that are initially hidden from Harry.
Perhaps the experiments by Cadmus would change Naruto in unexpected ways. His powers could be altered, and he might develop new abilities or lose some of his old ones. This could lead to a conflict within Naruto as he tries to come to terms with these changes. His friends in Konoha might initially be suspicious of him due to his altered state. But Naruto would strive to prove that he's still the same person at heart and use his newfound or remaining powers to protect his village from any threats related to Cadmus.
You could start by looking on popular fanfiction websites such as FanFiction.net or Archive of Our Own (AO3). These platforms have a vast collection of fanfictions, and there's a good chance you'll find 'naruto project cadmus fanfiction' there if it exists.
One interesting Young Justice Cadmus fanfiction could be about a young hero infiltrating Cadmus to uncover its darkest secrets. They might face various genetically engineered creatures and have to outwit the scientists there.
Perhaps an old enemy of Batman who has made a deal with Cadmus. They combine their knowledge and resources. This could be someone like Mr. Freeze, who has found a way to use Cadmus' genetic engineering to make himself even more powerful. His new form and abilities would pose a great challenge for Batman Beyond.
Miss Martian is another character that can be a main focus. In some fanfictions, she uses her powers to try and understand the inner workings of Cadmus, especially when it comes to the mental and emotional states of the genetically engineered beings there. Her telepathic abilities make her a key figure in uncovering Cadmus' secrets.
Another plot could involve a character from the original Cadmus in the Batman Beyond timeline. For example, a revived clone or an old scientist who has new plans. They could be using the advanced technology of the future to bring back old threats or create new ones. Batman Beyond would have to use his unique skills and gadgets to deal with this. He might also team up with some of the new heroes in the future Gotham to take on Cadmus.