Rukia would be extremely shocked and disappointed. She has always seen Ichigo as a force for good, and seeing him side with Aizen, who is the main antagonist, would be a huge blow to her. She might try to talk Ichigo out of it at first, and if that fails, she could become his enemy.
Well, anime can bring manga to a wider audience and introduce new fans to the source material. Also, the visual and audio elements of anime can enhance the appeal of the story presented in manga. On the other hand, manga can offer more detailed plots and character development that anime might have to condense due to time constraints.
Hermione would likely be devastated. She might go into a deep state of mourning, but also use her intelligence to try and figure out what led to Harry's death. Ron would be angry and heartbroken at the same time. He'd probably want to seek revenge if there was someone or something responsible.
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.
There could be friends who are initially shocked. They might not have expected Ichigo and Senna to start a family so soon. But after the initial surprise, they would come around and offer their congratulations. Maybe they would even share their own experiences of having children or being around pregnant friends.
Kakashi would likely be amused by the whole situation. He might give Naruto some tips on how to blend in better as a girl, using his own knowledge of disguise techniques. Iruka would be more concerned about the reasons behind Naruto dressing as a girl and would make sure Naruto is comfortable with it. He would also be there to support Naruto if any of the other villagers had a negative reaction.
Harry would be extremely shocked. He has always seen Snape as a complex figure, and Hermione capturing him would make him question a lot of things. He would likely try to get to the bottom of it and mediate between Hermione and Snape if possible.
Well, Anna would be frantic. She'd immediately set out to find Elsa, not caring about the danger. She might even team up with the Guardians without hesitation. Kristoff would be right by Anna's side, using his survival skills to try and track down Pitch's location. Olaf, being the innocent and loving character he is, would be heartbroken. He might try to cheer Elsa up from afar by singing or reminiscing about their good times, hoping it reached her somehow. The trolls, if they found out, would offer their wisdom and perhaps some magical aid to help in the rescue of Elsa from Pitch's clutches.
Luka, being her brother, would be super protective. He would constantly check on her, hold her hair if she needs to vomit, and try his best to comfort her. He might also sing a soft song to soothe her nerves, as music has a calming effect in the Miraculous Ladybug universe.