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.
There might be a fanfiction where Loki gets amnesia and the Avengers have to figure out what to do with him. Thor is torn between his loyalty to his brother and the safety of the team. Some Avengers want to lock Loki up, while others, like Black Widow, try to figure out if his amnesia is real or just a trick. In the end, they might discover a new side to Loki that was hidden all along.
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.
A lot of fanfiction focuses on Loki's redemption arc within the context of the Avengers. For example, Loki could be injured and the Avengers take him in instead of imprisoning him. This leads to him slowly seeing the value in their cause and starting to change his ways. He might start using his powers for good, like helping Thor understand some new magical threats, which also helps to strengthen the bond between him and the Avengers.
Another plotline might involve Loki getting caught in a time - loop within an Avengers - related adventure. He keeps reliving the same day, and each time he has to interact with the Avengers in different ways to try and break the loop. This could lead to some really comical and also tense situations as he tries to figure out what's going on while the Avengers are getting increasingly suspicious of his behavior.
One plotline could be Loki initially resisting the Avengers' attempts to adopt him. He might be suspicious of their motives, thinking it's a trick. But over time, as they show genuine care, he starts to open up. For example, Thor could be a key factor in getting Loki to trust the Avengers, as he vouches for their good intentions.
One possible plotline could be that future Loki comes with a warning about a new threat that the Avengers initially don't believe. For example, he might tell them about a powerful being from another dimension that is slowly making its way to Earth. Another plotline could involve future Loki trying to redeem himself in the eyes of the Avengers by helping them prevent a disaster that he was partly responsible for in his own timeline. He could use his knowledge of magic and trickery to outwit the new enemy.
One plot idea could be that Loki has been captured by a powerful new enemy who wants to use his knowledge of Asgardian magic. The Avengers find out and embark on a rescue mission. Along the way, they face various traps set by the enemy. Another could be that Loki fakes his own capture to draw out a threat that he can't handle alone, and the Avengers come to his aid not knowing it's a ruse at first.
One interesting 'Avengers meet Loki' fanfiction could be where Loki is actually forced to team up with the Avengers against a greater threat. Maybe a new, powerful enemy emerges that Loki realizes he can't defeat alone, and he has to use his wits and the Avengers' strength. In this story, there could be a lot of humorous exchanges as the Avengers are initially very suspicious of Loki.
In some 'Avengers and baby Loki' fanfictions, baby Loki could form a special bond with one of the Avengers, like Thor. Thor might be extra protective of his younger self in a way and try to shield baby Loki from the more judgmental Avengers while also teaching him about their family's history.