He might kill an enemy shinobi from another village. For instance, if there is a particularly aggressive and cruel shinobi from the Sand Village during the Chunin Exams who poses a great threat to Naruto's friends or the Leaf Village in general, Naruto could be forced to kill him in self - defense or to protect others.
In this kind of fanfiction, Naruto might have used his new and powerful jutsu that he developed secretly. Maybe it was a super - enhanced Rasengan with some special chakra nature added to it, which was strong enough to overpower Orochimaru.
In such a fanfiction, the plot could involve Naruto being pushed to the extreme during the Chunin Exams. Maybe he witnesses some great injustice or threat to his friends that makes him cross his moral line and kill. For example, if an enemy tries to assassinate Sasuke during the exams and Naruto, in a fit of rage and desperation to protect his friend, uses a powerful jutsu that ends up killing the attacker.
Yes, there might be such fanfics out there. Fanfic writers often explore alternative storylines, and this would be a very dark and unexpected twist to the original Naruto story. It goes against the strong bond and rivalry that Naruto and Sasuke have in the canon, but that's the allure of fanfiction - to see what could happen if things took a drastically different turn.
The other competitors in the Chunin Exams could also be the audience. They would probably have mixed reactions, some might laugh at him while others respect his boldness.
Sasuke could still be a major rival. Even though they are friends, the competitive spirit between them might flare up again during the exams.
In some fanfictions, Kakashi could also play a role. He is very knowledgeable and has seen the Rasengan in action. He might offer some tips on chakra control, which is crucial for Naruto to master the Rasengan.
It could be Orochimaru. He's always been interested in Naruto and has his own devious plans. He might frame Naruto during the Chunin Exams to create chaos and further his own goals of obtaining power and knowledge. Orochimaru could use his henchmen or his jutsu to make it look like Naruto is involved in some sort of treachery.
Even Kakashi could play a role. He might oversee Naruto's training and correct his mistakes, ensuring Naruto is well - prepared for the Chunin Exams.
Since Orochimaru had many experiments and secrets, his death at Naruto's hands in the Chunin Exams fanfiction could lead to a scramble for his research. Other villages or even some rogue ninjas might try to steal his notes and facilities. In Konoha, Naruto might be pressured to reveal what he knew about Orochimaru's plans and secrets. This could put him in a difficult position as he may not know everything. Also, Sasuke, who had a connection with Orochimaru, might have a complex reaction. He could be angry at Naruto for killing Orochimaru, or he could see it as a sign of Naruto's strength and be motivated to become stronger himself.
In this fanfiction scenario, Naruto and Yugito could have some really interesting interactions during the Chunin Exams. Maybe they start off as rivals, each determined to prove themselves in the exams. Naruto with his unwavering determination and Yugito with her unique skills. They might end up in a match against each other, and through the battle, they gain a newfound respect for one another's abilities.