One common theme is the clash of their personalities. Gilgamesh is proud and haughty, while Mordred is rebellious. Their interactions often involve power struggles and attempts to outwit each other.
Love and friendship are also common themes. An OC could develop a deep friendship or even fall in love with Mordred. This relationship can be complicated by Mordred's status as a Servant and the events of the Holy Grail War. It can also be a source of character development for both the OC and Mordred. For instance, Mordred might learn about different forms of love and loyalty through her relationship with the OC, while the OC might grow in courage and determination as they get closer to Mordred.
Yes, there are quite a few out there. Some focus on unique crossovers where the magic of Harry Potter's world combines with the lore of Fate Stay. For example, you might find ones where Mordred ends up at Hogwarts and has to adapt to the new magical environment. It's really interesting to see how different the two universes are and how the characters interact.
There are often fanfiction communities on Reddit as well. The r/fatestaynight subreddit might have some threads dedicated to OC and Mordred fanfiction. People often share their own works or recommend ones they've read. You can also look for Tumblr blogs that are focused on Fate Stay Night. Some bloggers are really into fanfiction and might have reblogged or written some interesting stories about OCs and Mordred.
You can try fanfiction websites like Archive of Our Own (AO3). It has a large collection of Fate fanfictions, and you can simply search for 'Gilgamesh x Mordred' there. A lot of talented writers post their works on AO3.
A plot where Mordred attends Hogwarts undercover could be very interesting. She could be on a secret mission while trying to fit in with the students and learn about the wizarding magic, which is very different from her own powers.
There could be. Fanfiction writers often come up with very creative and unexpected crossovers. In a 'fem Harry Potter is Mordred' fanfiction, the author might give the female Harry Potter some of Mordred's characteristics or a backstory related to the Arthurian lore. It could be an interesting exploration of different mythologies and fictional universes combined.
Mordred is a complex character. He's known for rebelling against King Arthur and causing significant chaos. Some versions show him as driven by ambition, while others present him as a victim of circumstances.