The fanfic might also focus on the themes of rebellion and sacrifice. The 'Black Rebellion' aspect can be expanded upon, like how the resistance fighters adapt to new threats. They could be facing a new type of weapon or a more brutal Britannian general. This would show their determination and the lengths they are willing to go to for freedom, similar to what was shown in the original series but with new twists.
The exploration of different relationships. In a fanfic, we might see unexpected romances or friendships develop. It could be between a Britannian and a member of the resistance, which adds a new layer of complexity to the story. This is different from the more straightforward relationships in the original anime.
One common theme is loyalty. Since the Black Knights are a group, many fanfictions explore the loyalty among its members, and how they deal with betrayals or doubts within the group. Another theme is the fight for justice. They are rebels, after all, and fanfictions often delve into their motives and the different ways they pursue justice in the Code Geass universe.
I'm not sure specifically about 'Code Geass Black Knights' fanfiction directly related to suicide. Fanfiction can cover a wide range of themes, but this is a rather dark and serious one. It might exist in some corners of the fanfiction community, but it's not a common or widely promoted type of story due to its disturbing nature.
In most cases, yes. Fanfiction is a form of creative work by fans, and as long as it doesn't violate any copyright laws in a major way (like using the original work for commercial gain without permission), it's generally okay to view. However, the legality can get a bit murky in some situations, for example, if the fanfiction contains elements that are too close to the original's plot in a way that could be seen as copyright infringement.
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.
One idea could be an OC who is a commoner but has a unique power that gets noticed by Lelouch. For example, the ability to manipulate sound waves which could be used for both stealth and attack. Another could be an OC from a foreign nation who has different moral and cultural values than the Britannians and Japanese, creating interesting conflicts. Or an OC who is a brilliant scientist working on a secret project that could change the balance of power in the Code Geass world.
Yes, it is. As a 'Code Geass' fan, it gives you more content related to the series. You get to explore the story further and might discover new aspects of the characters and the world.