On the other hand, some of the more sympathetic characters, like those who oppose the dark arts but also believe in redemption, might see it as a cry for help. They could try to find a way to reverse the curse, not because they like Bellatrix, but because they believe that no one should be subject to such a strange and demeaning self - curse. This could lead to an interesting dynamic where the 'good' and 'bad' characters interact in an unexpected way.
Some characters might be shocked and disgusted. For example, the more 'pure - blooded' and traditional wizards would see it as a perversion of the natural order. They would likely distance themselves from her, fearing that whatever dark magic caused this could be contagious.
Perhaps in the fanfic, Bellatrix is under the influence of some dark magic that forces her to curse herself in this way. It could be part of a larger plot where her enemies discover her in this state and use it to humiliate her. Since lactation is not a normal state for a witch like her, it would be a great source of embarrassment and vulnerability in a world full of rivalries and power struggles.
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 characters' reactions could vary widely. His close friends in the fanfic might be in a state of panic, crying and not knowing what to do. Enemies, on the other hand, might see it as an opportunity to take advantage, or they could also be secretly worried depending on the complexity of their relationships. And there could be those characters who are just bystanders, shocked at first and then trying to figure out what happened.
Haku would likely be very protective. He has a special bond with Chihiro already, so when she turns into a spirit, he would probably try to guide her through the changes. He might teach her how to use her new spiritual powers. No - Face, on the other hand, could be either curious or envious. Since No - Face is always in search of something, seeing Chihiro transform into a spirit might make him wonder if she has found a new kind of fulfillment. The bathhouse workers might be initially shocked and a bit afraid. They are used to dealing with normal spirits, but Chihiro's transformation is something unexpected and they might worry about how it will affect the balance in the bathhouse.
Nagisa would be completely devastated. She has a very deep connection with Tomoya, and his death would likely cause her to sink into a deep depression. She might even lose the will to live, especially if it happened suddenly. For example, if he died in an accident, she would be left with a sense of emptiness and longing for him.
Sasuke would be extremely suspicious. He has always seen Naruto as his rival and a symbol of the village's hope. If Naruto starts acting like Pein, Sasuke would think it's some kind of trick at first. He might even be ready to fight Naruto to figure out what's really going on.
Naruto's friends like Shikamaru and Kiba would likely be full of jokes. They would tease Naruko in a friendly way, but also be concerned. Shikamaru would probably be the first to think that there's more to it than meets the eye and start coming up with theories. Kiba, on the other hand, might be a bit more straightforward and just ask Naruko directly what's up, while his dog Akamaru would be sniffing around, adding to the chaos.
Sakura might be initially shocked but then she would be determined to help Naruto find out what's wrong. She could start researching in the hospital's library for any medical or historical records related to such a phenomenon.
Some characters like Ichigo would be extremely suspicious. Given his past battles with Aizen, he would not trust him easily. Ichigo might keep a close eye on Aizen's every move, waiting for any sign of his old devious ways to resurface. On the other hand, some of the more naive Shinigami might be easily fooled by Aizen's charm. They could see his joining as a great opportunity and welcome him with open arms, not realizing the potential danger.
Ruby would be deeply saddened. She might blame herself for not being able to protect Blake. Weiss would probably be in shock at first, then become more determined to fight against whatever caused Blake's death. Yang would be furious and seek revenge. She has a very close bond with Blake, and her death would likely fuel Yang's anger towards the enemy.