If ASL time - travels, Luffy's relationship with his brothers would be strengthened in new ways. They would have to rely on each other more as they face the unknowns of the past. For example, Ace might see a younger Luffy and be even more protective.
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.
If Walter goes back in time, his relationship with Skyler would be completely different. Instead of lying to her about his meth - making activities, he would be honest and they could build a more trusting relationship. They might even have a normal family life without all the secrecy and danger.
In a time - travel scenario, Anakin's relationship with his mother could be greatly altered. He could go back in time and save her from the Tusken Raiders. This would change his whole outlook on life and his path towards the dark side. Regarding his relationship with Palpatine, he would be aware of Palpatine's true nature from the start. So, he could either avoid Palpatine completely or try to expose him earlier. His relationship with other Jedi, like Ahsoka, could also be different. He could be a better teacher and mentor to her, as he has the experience of his future mistakes.
If Kakashi travels back in time, his relationship with his father would be completely different. Instead of the strained relationship due to his father's perceived failure, he could support his father and build a strong bond. With his students, if he travels to the future and then back, he might have a new perspective on how to train them. He could be more lenient or more strict depending on what he saw in the future of their development.
During time travel, Naruto might see Sasuke in a different light as they face historical events. Sasuke could also start to respect Naruto's leadership more. And Sakura, with her skills, would be more of an equal in their group. This could lead to a more balanced and harmonious relationship among the three. For example, in a time when they have to deal with a powerful enemy from the past, they'd have to trust each other completely, which would deepen their bond.
If Sakura travels back in time, her relationship with Sasuke would be very different. She could meet a younger Sasuke who hasn't been through all the traumas yet. She might be able to form a closer bond with him from the start and change his path. With Naruto, she could become a mentor - like figure if she travels to a time when he is younger, guiding him in a different way than in the original timeline.
His relationships with his guild members would also change. He could prevent some of their deaths or mistakes. For example, he might be able to stop Klein from getting separated from the group at the start of SAO. This would lead to a different dynamic within the guild, with more camaraderie and a sense of unity.
One interesting plot could be that Ace, Sabo, and Luffy travel back in time to when Gol D. Roger was still alive. They could try to prevent certain events that led to the current state of the One Piece world. Maybe they want to stop the tragedies that befell their families in the past.
One common theme is communication. Since ASL is a form of communication, in these fanfictions, it often becomes crucial in different time periods. Another theme is adaptation. The characters have to adapt to the new time they are in while still using ASL. And also, there's often a theme of discovery, like discovering how ASL was used or not used in the past.
Luffy's rubber ability might not change directly due to time travel, but his understanding of how to use it could be enhanced. For example, if he travels to a time where there are different fighting styles, he could incorporate new techniques. Robin's ability to sprout body parts on any surface could be used in really creative ways. If they travel to a time with different architecture, she could use the structures to her advantage in combat or for exploration in ways she hadn't thought of before.