Maybe Red Hood believes that Batman's methods are no longer effective. He could think that by killing Batman, he can take over Gotham and impose his own brand of justice, which might be more brutal but in his eyes more efficient. This would be a great plot point in fanfiction to explore different concepts of justice.
Catwoman can be a great character in such fanfiction. She has her own moral code that often clashes with Batman's. Her presence can create more tension and also add an element of romance. She could also interact with Red Hood in interesting ways, perhaps seeing some of herself in him.
Differing ideologies during the wizarding war. If James was seen as a threat to Snape's side (even if Snape was on the wrong side, from a moral perspective), Snape could justify killing him. For example, if James was too aggressive in fighting the Death Eaters and Snape thought it would lead to more bloodshed, he might take matters into his own hands to stop James.
One possible motive could be revenge. The Dursleys treated Harry awfully for years, so in fanfiction, he might reach a breaking point. Another could be self - defense if the Dursleys in the fanfiction were to take their abuse to an extreme level.
One possible motive could be jealousy. Hermione is highly intelligent and often outshines Draco in academics. In a twisted version of a rivalry, Draco's envy could turn into a deadly hatred. Another could be his family's influence. If the Malfoys push him to take extreme actions against Muggle - borns, Hermione would be a prime target.
A possible motive could be revenge. If a dragon had hurt someone he loved, like his father or Astrid, he might be driven to kill it. It would be a very emotional and difficult decision for him, but his love for his friends and family could push him to that extreme.
One possible motive could be jealousy. If Kiba were to gain more recognition in the village than Naruto in the fanfiction world, Naruto's insecurities could drive him to do something drastic like killing Kiba. But this is a huge departure from his usual self.
In fanfiction, the conflict between Red Hood and Batman often stems from their different ideologies. Red Hood, having experienced a darker path, might have a more extreme view on justice compared to Batman's no - kill rule.
Well, strength can be measured in different ways in the Batman vs Red Hood comic. If we're talking physical prowess, they're both quite capable. But in terms of strategy and determination, it varies from one encounter to another. So, there's no clear-cut answer as to who's stronger.
Perhaps Stiles discovers some dark secret about the alpha pack that endangers the entire town or the supernatural world he's a part of. In his sense of responsibility and his unique way of thinking, he figures that killing the alpha pack is the only solution to prevent a greater catastrophe. This can add a lot of depth to the fanfiction story, exploring Stiles' moral compass and his ability to make tough decisions.
Well, it could be that Kakashi is under some sort of dark spell or curse that makes him see Naruto as a threat to the village. In some fanfictions, there might be a situation where the village's safety is at stake and Kakashi believes that sacrificing Naruto is the only way to save everyone. Also, it could be a case of false information. If someone convinces Kakashi that Naruto has turned evil and is about to cause great harm, he might take the drastic step.