One interesting 'Harry Potter Star Trek crossover fanfic' is 'The Wizarding Federation'. It combines the magic of the Harry Potter universe with the advanced technology and exploration aspects of Star Trek. In this fanfic, Hogwarts is visited by a Starfleet crew, and there are some really cool interactions between the characters from both worlds, like Harry and Captain Kirk having a conversation about leadership and courage.
The novelty. It combines two very different and beloved universes. People love seeing how the magic of Harry Potter and the technology of Star Trek can interact.
Yes, there are. There are many creative fanfic stories that blend the universes of Star Trek and Harry Potter. Some might imagine the characters from each series interacting in unique ways, like Harry Potter characters using Starfleet technology or Star Trek characters attending Hogwarts. These fanfics can be found on various fanfiction websites.
A great plot point is the interaction between different forms of power. The power of the Force in Star Trek (if we consider things like the mind - melding and psychic abilities) and the magic in Harry Potter. How would a Jedi - like character from Star Trek fare against a powerful wizard? And how would they work together to face a common enemy? It creates a lot of interesting storylines.
One challenge is merging the two very different universes. Star Trek is based on science and technology, while Harry Potter is centered around magic. Writers need to find a way to make the two coexist plausibly. For example, how can magic work in a world where technology is so advanced? Another challenge is staying true to the characters of both series. Fans have a certain expectation of how Harry Potter or Captain Kirk should act, so any deviation might be off - putting.
Hermione Granger is also a very popular character in these crossovers. Her intelligence and thirst for knowledge would make her a great fit in the Star Trek universe. She could easily adapt to the technology - driven world of Starfleet, while still being able to use her magic when needed.
One interesting crossover could be the use of magic in the Star Trek universe. For example, a fanfiction might have a wizard or witch from Harry Potter end up on the Enterprise and use magic to solve some of the ship's problems, like a strange alien energy field that normal technology can't deal with.
There could be a fanfiction where the characters from both universes meet at a sort of interdimensional crossroads. For example, Hermione could team up with Spock. Hermione's vast knowledge and logical thinking, combined with Spock's Vulcan logic, could make for an interesting duo as they try to find a way back to their respective universes while also facing various challenges along the way.
It's hard to say just from 'reader si star trek fanfic'. If'reader' is a person, then no, a person isn't a Star Trek fanfic. But if it's a misspelling and it should be 'this' or something similar referring to a text, then it might be. It depends on the context really.
He could be a powerful being that the Star Trek crew encounters. Maybe he's been traveling through different dimensions and ends up in the Star Trek universe. His magic would be something completely new and strange to them.