Love - hate relationships are also quite common. Given their opposing natures, there could be a lot of tension that could either lead to intense dislike or, in some cases, an unexpected attraction. Writers often play with this dynamic, creating complex and interesting stories.
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.
One common theme is self - discovery. Both Mordred and the OC often go through a journey of understanding themselves better because of their relationship. Another theme is loyalty. They usually show great loyalty to each other in the face of various difficulties.
One common theme is the struggle for identity. Mordred already has her own issues regarding her identity in the Fate series, and when an oc is introduced, it often adds another layer to this exploration. For example, an oc might be from a different background that challenges Mordred's views on herself and her place in the world.
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.
The exploration of Gilgamesh's character is also a major theme. Many fanfictions use the crossover concept to dig deeper into his personality. They might show a softer side of him that was not fully explored in the original Fate series, or they might further emphasize his pride and arrogance in new and different situations, like when he's in a world full of magic users who don't recognize his kingly status immediately.
Love and romance are also common themes. She might be paired with other characters in the Fate universe, and the fanfictions explore how their relationships develop. This could be a complex relationship given her strong - willed and powerful nature. Additionally, some fanfictions may explore themes of loyalty, especially in relation to her role as a Servant and her relationship with her Master.
Another theme could be adventure. They might go on quests together, facing various challenges that test their relationship and individual strengths. For example, they could be on a mission to save a kingdom or defeat a powerful enemy.
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.
The theme of fate also often appears. Given their roles in the Fate universe, fanfictions may explore how their fates are intertwined. Whether it's a pre - determined meeting or a struggle against the strings of fate that bind them, this theme adds an extra layer of depth to their relationship in the stories.
Another theme is the clash of ideals. Gilgamesh has his own view of kingship which is often at odds with Saber's. This conflict of ideals can lead to some really intense and interesting storylines. For example, in some fanfictions, they have long debates about what it truly means to be a king.
Another theme is often the clash of different cultures or backgrounds. Gilgamesh comes from a very different world compared to Shiro, and fanfictions might explore how they bridge those gaps, whether it's in terms of values, fighting styles, or social hierarchies.