Obviously, the RWBY team - Ruby, Weiss, Blake, and Yang - are often involved. Ruby might be the most likely to initially trust Roman if he shows signs of changing. Yang could be more skeptical, leading to some interesting conflicts.
Ozpin could also play a role. He might see Roman's survival as an opportunity to gain an ally in the fight against Salem. Ozpin would likely be cautious but intrigued by Roman's potential to change and contribute to the cause.
One interesting plotline could be Roman teaming up with the main characters against a new common enemy. Maybe he has some inside knowledge that could help them defeat this powerful foe.
Obviously, Anakin himself is the central character. Luke would also be a major figure as he would be interacting with his father in a different way than in the original ending. Leia might also play a significant role, perhaps struggling to accept her father's new existence and having to come to terms with her own connection to the Force through him.
Weiss Schnee could also be involved. Her haughty attitude in the beginning could lead to situations where she is humiliated. For instance, if she makes a wrong assumption about someone and is then proven wrong in a very public way.
Obviously, the Reaper is a main character. Ruby Rose is also often involved as she is one of the central characters in RWBY and her connection to the concept of death (which the Reaper represents in a way) makes for interesting interactions. Weiss Schnee can also be seen in some fanfictions, as her family's past and her own story can cross paths with the Reaper's storyline in creative ways.
Ruby is often involved. Since she's the main protagonist in RWBY, it makes sense for her to interact with Nightcrawler in fanfictions. Their different powers and personalities can create interesting dynamics.
Obviously Ruby herself is a main character. She is the center of the reincarnation concept. Weiss, Blake, and Yang are also important as they are Ruby's team members. Their relationships with Ruby are likely to be explored in different ways in the fanfiction due to Ruby's reincarnation. Ozpin could also be involved as he has a lot of knowledge about the history and secrets of Remnant, and Ruby's reincarnation might be related to some of those deeper mysteries.
Ruby's sister Yang is very likely to be involved. Yang is protective of Ruby, so if the ruby slippers put Ruby in any sort of danger, Yang would be right there. Crescent Rose, Ruby's weapon, could almost be considered a character in a sense in these fanfictions. Since the slippers' power might interact with Ruby's fighting style and thus her weapon. And then there are the villains from the RWBY universe, such as the Grimm, who could be attracted to the power of the slippers and constantly be a threat to Ruby while she has them.
Ruby Rose is often involved. Given her role as a main character in RWBY, it's easy to imagine her having some sort of encounter or connection with the God of Light. Her silver eyes, which already have special significance in the series, could be further explored in relation to the God of Light.
Ruby Rose is often involved. Her speed and scythe - wielding skills can be really useful on a Dreadnought battleship, whether it's for fighting Grimm or helping with ship - related tasks. Weiss Schnee is also common. Her ice powers can be used for defense or to cool down overheating ship systems.
Yang is another character often seen in'mind control rwby fanfiction'. Her hot - tempered nature and her love for her sister Ruby can create interesting storylines when she's under mind control. For instance, she might be made to fight Ruby without realizing it. And Cinder could be the one causing the mind control in many of these stories, as she's a major antagonist in RWBY and has the power and motivation to manipulate others in this way.