Perhaps they travel to a time when the Geass power was first created. Lelouch could try to change the nature of the Geass power to make it less destructive. This would involve him interacting with the original creators of Geass and trying to persuade them to modify it. Meanwhile, Nunnally could be learning about the history of their world from a different perspective, which would help them in their future plans.
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.
A lemon fanfiction usually contains romantic or sensual elements. In the context of Code Geass, Lelouch and Nunnally have a complex relationship. In fanfiction, it might explore a different side of their bond, perhaps a more romantic or even unorthodox one. However, it's important to note that such fanfictions might deviate from the original plot and characterizations of the anime.
One can expect a re - imagining of their relationship. Since it's a lemon fanfiction, there may be some romantic or emotional scenes that are more intense than in the original. It might also focus on the characters' inner thoughts and feelings towards each other in a more intimate way.
There is a fanfic called 'Lelouch's Time Travel Adventure'. In it, Lelouch travels back in time to a point before the start of the series. He uses his knowledge of the future to try and prevent the events that led to the sad state of the world in the original story. It has some really cool moments where he outsmarts his enemies using future knowledge, and the way the author writes his internal monologues is very interesting, making it a great read for Code Geass fans.
Time travel can greatly expand Lelouch's character development. When he travels back in time, he gets a second chance. This makes him more cautious as he doesn't want to repeat the same mistakes. For example, he might be more careful in his relationships with Suzaku and others, knowing how things turned out before.
One common theme is redemption. Since she's traveling back in time, the female Lelouch often tries to right the wrongs she did in the original timeline. Another theme is the exploration of different relationships. For instance, how her relationships with other characters change when she has the knowledge of the future.
In Code Geass fanfic, Nunnally is often a complex character. She is usually depicted as a symbol of innocence and hope. Writers might explore her relationship with Lelouch in different ways. For example, some fanfics might focus on how she would react if she knew all of Lelouch's secrets and plans. Her blindness also adds an interesting layer to her character, as it can be used to show her inner strength and vulnerability simultaneously.
Often, in these fanfictions, the exploration of the characters' motives is crucial. Lelouch's desire to protect Nunnally may drive his actions in the time - travel scenarios even more strongly. Also, the concept of fate is played with. They might be trying to break free from a pre - determined fate that was set in the original story.
There's also 'Female Lelouch: Time's Redemption'. In this fanfiction, the female Lelouch's time travel leads to some really unexpected alliances. For example, she teams up with some characters that were previously her enemies in the original timeline. It's full of plot twists and turns.