One great story could be where Teen Loki has to team up with the Avengers against a common enemy. Maybe an ancient Asgardian threat resurfaces and Loki, despite his mischievous nature, realizes he needs to work with them. In this fanfiction, Loki uses his magic in creative ways to help the Avengers in battles they couldn't win on their own.
You can start by looking on Archive of Our Own (AO3). It has a large collection of fanfiction, and you can easily search for 'Avengers and Teen Loki' in the search bar. There are different tags and filters you can use to narrow down the results based on your preferences, like the genre or the rating of the story.
One interesting Loki and Avengers fanfiction could be where Loki is forced to team up with the Avengers against a greater threat. Maybe an ancient evil that even Loki realizes is too dangerous to face alone. He grudgingly works with them, and along the way, there are lots of humorous exchanges as the Avengers don't trust him at first.
One great 'Avengers Academy Loki Fanfic' could be one where Loki uses his trickery in the academy setting in a humorous way. For example, he might play pranks on the other students but in the end, it leads to a valuable lesson about friendship and acceptance.
There could be a fanfiction where the Avengers are forced to watch Loki's fan - created adventures in an alternate universe. In this, Loki might be a hero instead of a villain, and the Avengers have to come to terms with this new version of him. They may start to question their own perceptions of good and evil.
One interesting Young Avengers Loki fanfiction could be where Loki has to mentor one of the Young Avengers. He might use his trickster ways to teach them about the complexity of magic and the importance of out - thinking opponents. For example, he could help Wiccan control his powerful magic by showing him some of the more unorthodox methods he learned in Asgard.
One interesting story could be about Thor and Loki having to team up against a new, powerful enemy that neither of them can face alone. This forces them to put aside their differences and use their combined powers and wits to save Asgard.
Redemption is a very common theme. Since Loki has a rather villainous past in the original lore, many fanfictions focus on him trying to make up for his wrongdoings and be accepted as a good guy by the Avengers.
One great example could be a story where the Avengers initially suspect Loki but then realize he's been wrongly judged. In this fanfiction, Loki might use his magic to help the Avengers in a battle against a common enemy, like a powerful new villain from another dimension. This shows his good side as he puts aside his past differences with the team.
There's a fanfiction titled 'Good Loki Among the Avengers'. It's about Loki being sent to Earth as a sort of undercover agent for Asgard but ends up really bonding with the Avengers. He uses his trickster skills for good, like helping them outwit villains in really clever ways. It's a great read if you like to see Loki in a more positive light within the Avengers' universe.
Loki's character development can also involve him learning about the value of teamwork and friendship. As he interacts with the Avengers more, he starts to see the benefits of working together rather than against them. He might share his knowledge of magic and Asgardian lore with the team, which in turn helps them in their battles. This exchange also helps him grow as a character and become more integrated into the group.