One thing that could lead to Naruto being a cold killer in fanfiction is if the story is set in an alternate universe where the values of the Naruto world are completely flipped. For instance, if in this universe, strength is the only thing that matters and weakness is despised. Naruto, being a powerful ninja, might adapt to this cruel world view and become a cold killer. Also, if he is betrayed by those he trusts deeply in the fanfiction, it could shatter his positive view of the world and turn him into a cold - blooded avenger.
A possible reason could be a tragic backstory that twists his personality. For example, if he witnessed something extremely traumatic, like the death of all his friends at a young age due to the actions of a certain group, it might turn him into a cold killer seeking revenge in fanfiction.
One possibility is if he faced extreme betrayal in fanfiction. For example, if his friends turned on him for some reason, it could lead him to become cold - hearted as a form of self - protection. Another factor could be if he lost someone very dear to him in a particularly cruel way and then closed off his emotions.
Some writers may be attempting to analyze the character from a different psychological perspective. By portraying Naruto as a cold - blooded killer, they could be exploring how his upbringing or the events in the Naruto universe could have potentially led to a different, more sinister outcome. It might also be a form of creative rebellion against the traditional view of Naruto as a hero. However, this is a very extreme deviation from the original character, and not all fans would be receptive to such a portrayal.
Sasuke could potentially be the main character in a 'naruto cold killer' fanfic. He already has that brooding and somewhat cold personality. In this fanfiction, he could take his thirst for revenge to an extreme level and become a cold - blooded killer, hunting down those he believes are responsible for his clan's massacre. This would be a very different take on his character compared to the original Naruto story.
In some fanfiction, Naruto might be depicted as a cold killer, but this goes against his canonical character. In the original Naruto series, he is a warm - hearted and determined ninja who values friendship and peace. However, in the realm of fanfiction, authors can take creative liberties and present a very different version of him.
Some writers could be exploring the 'what if' scenarios. They might wonder what would happen if Naruto had a different upbringing or faced different traumas that could turn him into a cold - hearted killer. It's a way of delving deeper into the character's potential under extreme circumstances. Also, it could be a form of creative rebellion against the typical positive portrayal of Naruto in the main series.
One possibility could be a great tragedy that befalls him. For example, if all his friends were brutally killed in front of him by an enemy he couldn't defeat at that time. This might shatter his belief in the goodness of the world and drive him to become cold - blooded in order to seek revenge. He would start to see killing as the only way to get justice.
No. Naruto is known for his warm - hearted and determined nature in the original series. Fanfiction that portrays him as a cold - blooded killer goes against the fundamental character traits that the majority of fans love about him.
In fanfic, a tragic backstory that was different from his original one could lead to Naruto being cold - hearted. Maybe if he had been abandoned by the whole village instead of just being shunned by some, he could grow up bitter and cold. Also, if he had to make really tough decisions that cost him a lot, like sacrificing friends for the greater good in the fanfic world, it might harden his heart.
One idea could be that the cold killer is a rogue ninja who was once a part of a secret Anbu - like organization in the Naruto world. They have a tragic past that made them turn cold - hearted. For example, they witnessed their entire clan being massacred by a powerful enemy. Another plot could involve the cold killer being hired to assassinate a major Naruto character, but during the mission, they start to question their own motives and actions when they learn more about the target. Maybe they find out that the target is not as bad as they initially thought.
It could be due to a new jutsu he's trying to master that has some side effects on his emotions. Maybe it's a powerful ice - based jutsu that's making him cold in nature as well.