In some RWBY deaged fanfiction, a cool plotline is the changed relationships. Yang, now deaged, might look at Blake in a more innocent way, and their friendship could develop in a really sweet and different manner. Maybe they start sharing secrets like little kids do, and it deepens their bond in a unique way.
A great plotline might involve the deaged characters interacting with their younger selves' memories. Weiss could be haunted by her family's expectations in a new light, as if seeing them for the first time all over again. This could lead to her making different choices and growing in a whole new direction.
One interesting plotline could be Severus having to take care of a deaged Harry. He might struggle with his initial dislike for Harry but gradually grow to understand him better in this new situation. For example, he could teach the young Harry some basic potions skills, which would be a unique bonding experience.
One interesting plotline could be Harry and Draco being deaged and having to rely on each other in a world that seems new to them again. They might form an unexpected friendship as they don't have the pre - conceived notions from their older selves. For example, they could team up to solve a mystery in Hogwarts that only they, with their combined knowledge from before, can figure out.
One possible plotline could be Anakin having to re - learn the ways of the Force as a child while also dealing with his past memories. Another might be how the other Jedi react to this de - aged Anakin, whether with suspicion or a sense of protectiveness.
One idea could be Ruby having to relearn her combat skills while being deaged. It would add an element of struggle and growth as she tries to regain her former abilities. Maybe she forms new friendships with characters she already knew in a different way because of her new, younger perspective.
A typical plotline in Loki deaged fanfiction is Loki being deaged due to some magical mishap. This then leads to him being in a situation where he has to rely on others, which is a big change for him. For instance, he might have to rely on the Avengers (if it's set in that universe) for help. Another aspect could be that deaged Loki has to face his insecurities from his childhood all over again. This can be really interesting as it shows a different side of Loki, a more vulnerable side that we don't often see in the original stories. There are also fanfictions where deaged Loki tries to regain his old age as quickly as possible while still causing some trouble along the way.
One possible plotline could be a character sacrificing their own powers to save their friends from a powerful enemy. For example, Ruby might give up her Silver - eyed Warrior abilities to stop Salem's latest scheme and protect her team.
Well, in some rwby mugetsu fanfiction, there might be a plotline where the characters have to adapt to a new world that combines the two settings. They could struggle with understanding different cultures and magic systems. Maybe Weiss has to learn how to use her Glyphs in a world where the rules of magic are more like those in Mugetsu. This would lead to her character growth as she overcomes these challenges.
One possible plotline could be a character facing public shaming in the RWBY universe, perhaps due to a failed mission or a misjudgment. Another could involve a character being humiliated in a social setting within the school or among their team.
Another plotline could involve the reincarnated character trying to change the fates of the main RWBY characters. They might know about certain events that are going to happen in the future of the RWBY story and work towards preventing tragedies or enhancing the characters' growth in different ways. Maybe they try to save Pyrrha from her doomed fate at the hands of Cinder.
A unique plotline could be Percy being deaged and having to hide his identity from the new demigods at Camp Half - Blood. He has to pretend he's a new camper while secretly trying to find a way to reverse the deaging.