Blake might be a bit more reserved in her reaction. She would observe Ruby carefully, trying to understand how to best help her. Blake has a more introspective nature, and she would likely think about the long - term implications of Ruby being deaged. She might also share some of her own experiences of feeling lost or different to help Ruby cope with her new situation.
Weiss would probably be very protective at first. She has always had a bit of a mother - hen side to her, and seeing Ruby in a more vulnerable, deaged state would bring that out. She would likely try to keep Ruby out of trouble and make sure she was taking care of herself.
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.
The other characters would be shocked. Weiss would probably be the first to try and figure out what's wrong with Ruby. Blake would be worried about Ruby losing her way, and Yang would be furious. Yang might even go on a solo mission to bring Ruby back, not fully trusting the rest of the team to handle it delicately. The rest of the characters like Jaune and Nora would also be in disbelief and would start planning ways to rescue Ruby.
At first, Batman would be shocked and a bit confused. But quickly, his detective instincts would kick in. He would view the deaged Joker as a new and unexpected threat. He'd start gathering information about how the deaging occurred, in case it was part of a larger, more sinister plan. Batman would also be very careful not to underestimate the deaged Joker. He might try to isolate the Joker in a secure location to prevent him from causing chaos in Gotham. And he'd be constantly on the lookout for any signs of the Joker's old, devious self emerging from this new, younger form.
Yang would be completely heartbroken. She'd likely go through a period of intense grief and anger, possibly even blaming herself for not being able to protect Ruby. Weiss would be deeply affected too. She might become more reserved and solemn, vowing to use her skills to uphold Ruby's ideals. Blake would be inspired by Ruby's sacrifice to be more active in fighting against the darkness. She might see it as a call to arms to make Ruby's sacrifice not be in vain.
The other members of Team RWBY would be deeply affected. They would start to question their own abilities and the purpose of their fight. Some might withdraw into themselves, like a broken Weiss who shuts out the world for a while. Yang, on the other hand, could become reckless in her pursuit of vengeance, endangering herself and others. Blake would try to hold the team together, but she would also be mourning privately. The other friends and allies in the RWBY universe would also be in mourning. Qrow might blame himself for not being there to protect Ruby, and Ozpin would see it as a great setback in the fight against evil.
In this werewolf Ruby fanfiction concept, Ruby's character would develop in several ways. First, she'd have to deal with the physical changes and the new powers that come with being a werewolf. This would make her more self - aware as she discovers new limits and capabilities. Emotionally, she might feel isolated at first, as she's different from her friends. But as she learns to control her werewolf form, she'd grow in confidence. Also, her relationship with her weapon Crescent Rose might change. She could find new ways to use it in combat, perhaps incorporating more of her werewolf - like agility and strength.
She might be more guarded. Qrow is a cautious person, and if he raised Ruby, she would likely pick up on some of his wariness. So instead of being as open and naive as in the original series, she could be more hesitant to trust new people right away.
Emerald might be a character in this fanfiction. She could start as an enemy, trying to steal the Fall Maiden power from Ruby for Cinder. But as the story progresses, she might see the good in Ruby and switch sides. Neptune could also be there, providing some comic relief in the midst of all the serious Maiden - related business. And Glynda could be involved in training Ruby to control her new powers.
Ruby is often a popular choice. Her innocent and determined nature can be explored in new ways when she's deaged. Fans like to see how she would interact with the world around her with a child - like perspective while still having that spark of heroism.
With Weiss, their relationship could be more strained at first. Since Weiss has some preconceived notions about Faunus, she might be initially distrustful of Ruby. But as time goes on, they could overcome this. With Blake, they might bond more deeply as they both share the Faunus experience in a way. And with Yang, Yang would be very protective of Ruby, especially if Ruby faced any discrimination because of being a Faunus.