Well, in the fanfic, Bruce would probably become more withdrawn.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.
Naruto would first be extremely confused by the rules of the Death Note. His understanding of power and its consequences is rooted in his ninja training and his own moral compass. The Death Note's rules, which seem so simple yet so deadly, would be completely foreign to him. He would question why anyone would create such a thing and would be very hesitant to even consider using it, as it goes against everything he stands for in his world of ninjas, friendship, and protecting the innocent.
Some fans are heartbroken. Eren is a very popular character, and his death can be a huge emotional blow. They might write comments expressing their sadness and disappointment.
He might be shocked. The fanfiction could show his friends or himself in situations that are completely different from what he knows. For instance, if it shows him losing to a minor villain, it would be very unexpected for him.
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.
She might react with caution at first. Given that Death Eaters are known for their cruelty, Hermione would be smart to be on her guard. She would likely start by gathering information about the escaped Death Eater, like his known abilities and any possible weaknesses.
In the fanfiction, the Avengers would likely be devastated. Captain America might feel a sense of guilt for not protecting Spider - Man better. Iron Man could be filled with rage and vow to take revenge on whoever was responsible. Thor would probably be solemn and use his strength to seek justice. Overall, their reactions would be a mix of grief, anger, and determination.