Well, in the fanfic, Bruce would probably become more withdrawn. He'd brood over Jason's death, questioning his methods and his role as a mentor. Dick would be angry at the world, especially at the villains who might have been involved. Tim, on the other hand, would be more determined to prove that he can be a worthy Robin, but also carry the pain of losing Jason. Alfred would be the one constant, trying to comfort everyone with his wisdom and care. It's a really tragic event for the Batfamily and their reactions would be complex and full of emotions.
Jason Todd's death in fanfics is like a bomb that explodes within the Batfamily. For the Batfamily, it changes the whole dynamic. Alfred, for instance, is deeply saddened and tries to hold the family together while also mourning privately. Barbara Gordon, who has her own connection to the family, may see the danger of their vigilante lifestyle more clearly. And the new Robin, whoever that may be, has to carry the weight of living up to a legacy that ended so tragically. It's a complex web of emotions and changes that the fanfics explore in great detail.
Dick's reaction is also very sad. He was close to Jason and to see him die would be like losing a part of himself. He might become more reckless in his actions, trying to avenge Jason, which shows how deeply affected he is.
In many fanfics, the Bat Family is often devastated. Bruce might be filled with guilt, blaming himself for not being able to protect Jason. Dick could be angry and determined to find out who was responsible. Tim might feel a sense of loss and also a strange connection to Jason, as he took on the Robin mantle after him.
One great 'Batfamily Jason Todd Death' fanfic is 'Under the Red Hood'. It delves deep into the aftermath of his death and how it affects the Batfamily. The story shows the complex emotions of the characters, especially Batman's guilt and how it changes his relationship with the other members. Another interesting one might be those that focus on how Jason's death haunts the younger members of the Batfamily who grew up hearing about him.
Twilight Sparkle would probably be devastated. She looked up to Celestia as a mentor, so she might go into a state of deep mourning at first. But then, she could be motivated to try and fill the void Celestia left, using all the knowledge Celestia had imparted to her.
Some Death Eaters might be angry. They have a certain self - image and ideology in the original story, and if fanfic distorts that in a way they don't like, they would not be happy. For instance, if a fanfic makes them out to be weak or cowardly, they would likely react negatively. However, others might be more open - minded and see it as an interesting alternative view of their world, but this would be a minority among them, as they are generally quite set in their ways.
He would probably be shocked. The fanfic might have some very different takes on combat and characters that he's not used to.
Sasuke would likely be devastated. Despite their past differences, Naruto was his rival and in a way, his closest friend. He might go into a deep state of regret and isolation. Sakura would be heart - broken. She loved Naruto, and his death would be a huge blow to her. She might become more withdrawn and focus all her energy on her medical ninjutsu. Kakashi would be filled with a sense of failure. He was Naruto's teacher, and he would feel responsible for not being able to protect him.
Her friends like Rex would be heartbroken. He has fought alongside her for so long. Her death would make him feel like he has lost a part of his family. He might become more withdrawn or even more determined to fight in her memory.
Sakura would be devastated. She has known Naruto for a long time and has seen him grow from a loud - mouthed kid to a great ninja. His death would make her question everything. She might become more withdrawn and serious. Hinata would be heartbroken. She had deep feelings for Naruto. She might even lose her will to fight for a while.