Their meeting would likely be filled with suspicion at first. Nick Fury is used to dealing with all sorts of strange things, but magic from the Harry Potter world would be a new concept. Hermione, on the other hand, would be cautious around this unknown figure from a world without magic. She might even try to use a spell on him to protect herself if she felt threatened.
A more comical fanfiction could involve Hermione trying to teach Nick Fury about magic, and Fury being completely baffled but also intrigued. He would be constantly trying to find ways to use magic in S.H.I.E.L.D.'s operations, while Hermione is just trying to make sure he doesn't misuse it. It would be a fun clash of two very different worlds and personalities.
Percy would probably be a bit wary at first. He's used to the demigod world and Fury's whole S.H.I.E.L.D. thing would seem really different. But Fury would be all business. He'd likely be sizing Percy up, trying to figure out how to best use his powers.
In the comics, Nick Fury is indeed shown as black. This portrayal has been consistent over time and is an important aspect of the character's representation.
Yes. Nick Fury is black in the comics. This has been a consistent part of his character design and has been maintained throughout various comic storylines and adaptations.
A great plot point could be Percy introducing Nick Fury to the world of Greek gods. Fury, being the strategic mastermind he is, would try to figure out how to use this knowledge to protect the Earth better. Meanwhile, Percy is falling for Fury's no - nonsense attitude and leadership. Another plot point could be them going on a mission together to retrieve a powerful artifact that has both mythological and technological significance. The differences in their worlds and how they handle the situation could be really interesting.