For Suzaku, he could be influenced to break free from his self - imposed chains of loyalty to Britannia much faster. Fanfiction often explores his internal conflict in greater depth. If he were aware of these interpretations, he might start to question the system he serves and his own role in it more quickly, leading to a more decisive change in his character arc.
Lelouch's development would be interesting. In fanfiction, his character can be portrayed in many different ways. If he learned this, he might adapt some of the more positive traits from those versions. Maybe he'd become more empathetic earlier in his quest for justice, which could change how he interacts with his allies like C.C. and his sister Nunnally.
It could also create chaos. The relationships between characters would be severely affected. Kallen, if aware of certain fanfiction versions of her story, might react strongly. She could either be inspired to fight harder for her beliefs or become confused about her role and identity in the grand scheme of things. Fanfiction often takes creative liberties, and these new understandings could completely rewrite the dynamics among the characters.
The relationship between C.C. and Rukia would be quite complex. C.C. has a very mysterious and detached personality, while Rukia is more duty - bound and has a strong sense of camaraderie. They could start off as rivals, both being strong female characters with unique powers. However, as they get to know each other's pasts and motives, they might develop a grudging respect. C.C. might be intrigued by Rukia's connection to the Soul Society, and Rukia could be curious about C.C.'s immortality and her role in Lelouch's life.
For Naruto, his neglected past can be the driving force for his growth in the fanfiction. In the Code Geass world, he could start as a lost soul but gradually learn from the experiences there. For example, seeing how Lelouch manipulates the situation, Naruto might start to think more strategically about his actions. His character development could be about becoming more than just a powerful ninja but also a smart leader.
Imagine if the Geass power could be used to control magical creatures in the Harry Potter world. Lelouch could use his Geass on a Hippogriff or a dragon to do his bidding. At the same time, wizards and witches could use their magic to enhance the Geass. For example, a spell could be cast on a Geass user to make their power last longer or be more powerful. And the Hogwarts houses could each have a different approach to using the combined abilities. Gryffindors might be more bold in using the new powers, while Ravenclaws would be more strategic and Hufflepuffs more ethical in their use.
Lelouch's character would likely become more cautious. Knowing the consequences of his past actions through time travel, he might think twice before making rash decisions. For example, he might not be as quick to use his Geass power without considering all the long - term effects.
Characters can be developed by giving the gamer character new goals. For example, if the gamer is in the Code Geass world, they might start with just wanting to survive but then develop a goal of overthrowing the Britannian regime for the good of the people. As for existing characters like Lelouch, they can be developed further by having interactions with the gamer. Lelouch could learn new strategies from the gamer's game - like thinking.
C.C. might view it with a sense of detachment at first. But then she might realize that Lelouch is becoming more attached to Kallen in a way that could potentially change their own relationship. She might start to feel a bit left out or even jealous, as she has been by Lelouch's side for a long time and has her own unique bond with him.
The relationship between the Black Knights and Lelouch would also change. If Lelouch goes back in time and is more strategic from the beginning, the Black Knights might be more unified and loyal to him. They would see his long - term vision more clearly and be more willing to follow his every command, which could lead to a more powerful and efficient resistance against Britannia.
For the OC, start by defining their backstory. Where are they from? What experiences have shaped them? If they are from a lower - class area in Britannia, they might have a different perspective on the empire compared to Cornelia. Then, think about their goals. Are they seeking revenge, justice, or something else? As for Cornelia, explore her loyalty to Britannia deeper. Show her internal conflicts, like her doubts about some of Britannia's actions. Also, in their interactions, let their characters evolve. For example, if the OC challenges Cornelia's beliefs, she could start to question herself more, and the OC could learn to be more diplomatic from Cornelia.
First, study the existing world of Code Geass. Know the politics, the social hierarchy, and the technology. For example, if your OC is a Britannian, they should act according to the values and norms of that society. Second, give your OC a clear motivation. It could be revenge, love, or a desire for power. And third, don't make them overpowered. Even if they have a special ability, it should have limitations.