One possible consequence could be emotional turmoil. Naruto might suffer from nightmares or guilt, which could affect his performance in future battles and his relationships with his friends. He might become more withdrawn as he tries to deal with what he has done.
In some fanfictions, Naruto's first kill might be described as a moment of great turmoil. He could be forced into a situation where it's a matter of self - defense or protecting his comrades. It might be a difficult decision for him, given his generally kind - hearted nature. The description could include his hesitation, the look in his eyes as he realizes there's no other option, and the way his hands might tremble as he makes the fatal strike.
One common theme could be the coming - of - age aspect. Naruto's first kill might mark a significant shift in his character, from an innocent ninja - in - training to someone who has faced the harsh reality of combat.
One way to find good 'naruto first kill fanfiction' is to look at the reviews and ratings of Naruto fanfics in general. Some stories that are highly rated might have elements related to the first kill. You can also follow some popular Naruto fanfic authors. They might have written or be planning to write something that involves this concept.
In the Naruto canon, Naruto would never kill his mom. However, in some extremely dark and non - canonical fanfictions, the author might create such a scenario for shock value. But this goes completely against the spirit of the original series. Naruto is a story about love, friendship and growth, and such a plot is a very perverted deviation from it.
If such a fanfiction exists, a possible motive could be some kind of mind - control. Maybe an enemy uses a powerful genjutsu on Naruto, causing him to lose his sense of self and attack his mom. But this is still a very far - fetched and unethical concept within the Naruto world.
One possible reason could be to gain more power. Maybe he thought that emotions were holding him back from reaching his full potential as a ninja. He might have seen other powerful ninjas who seemed to be emotionless and thought that was the way to go.
One possible motive could be if his brother was somehow a threat to the village. Naruto is very loyal to Konoha, so if his brother was planning to destroy it or harm its people, Naruto might feel compelled to stop him at all costs.
His relationship with his sensei, Kakashi, would also change. Kakashi would have to train Naruto differently, focusing on how to utilize his water body to its fullest. Naruto might be more in sync with Kakashi's chakra - control teachings, as water is all about flow and control. Also, Naruto could use his water form to play pranks on Kakashi in new and unexpected ways.