I'm not entirely sure as it could vary greatly. But generally, it might be a fan - created story about Naruto and Hinata set in the academy days. It could focus on their relationship development, like how they interacted as students, and perhaps include some romantic or comical elements specific to their characters.
You can try looking on fanfiction websites such as FanFiction.net or Archive of Our Own (AO3). They have a large collection of Naruto - related fanfictions, and you might be able to find the 'naruto x hinata academy' ones there.
One possible antagonist could be a jealous student. Maybe someone who has a crush on Hinata and doesn't like Naruto getting close to her. This student could try to sabotage their projects or spread false rumors about them at the academy.
Often, these fanfictions focus on the relationship between Hinata and Naruto in a more romantic and sometimes intense way. They might explore their emotions and interactions in greater depth compared to the original series.
I'm not sure if it's popular. There are so many different types of fanfictions out there that it's hard to gauge the popularity of just this one. It might be popular among a small group of fans who are interested in exploring darker versions of Naruto and Hinata's relationship.
In some fanfictions, there could be a time - travel element. Naruto and Hinata are sent back to their academy days. They use their future knowledge to change some events in the academy. This could include preventing some bullies from picking on other students or even changing the way some of the lessons are taught.
In this type of fanfiction, their relationship could develop through shared classes. For example, they might be paired for a project in a ninja skills class. Naruto, with his determination, could inspire Hinata to be more assertive. And Hinata's kindness would draw Naruto closer to her. They could also meet during lunch breaks, where Hinata might share her home - made bento with Naruto, starting a sweet tradition between them.
One sign is that Hinata blushes a lot around Naruto. Whenever he is near, her cheeks turn red as she gets flustered. Another sign is that she is always stealing glances at him. During classes or in the academy courtyard, her eyes will often seek him out without her realizing it. Also, she might stutter or get tongue - tied when trying to talk to Naruto, which shows her nervousness because of her crush.
Well, usually in such fanfictions, Hinata's crush might develop through small, everyday interactions at the academy. For example, Naruto might unknowingly do something heroic or kind, and Hinata, being the shy and observant girl she is, would notice and her feelings would grow deeper each time. Maybe Naruto stands up to a bully for a younger student, and Hinata sees his selfless side, making her admire him even more.
I'm not sure if there is a specific 'evil naruto x hinata lemon fanfiction' available. Fanfiction is a vast and diverse field, and while there may be many Naruto - Hinata fanfictions, the 'evil naruto' and 'lemon' (which often implies sexual content in fanfiction terms) combination might not be as common or might even violate some fanfiction site's rules.