Well, obviously Loki is one of the main characters. Then there are the Young Avengers members. For instance, Wiccan, who has powerful magic abilities, and his relationship with Loki can be really interesting as they both have a connection to magic. Another main character could be Kate Bishop, Hawkeye of the Young Avengers. Her no - nonsense attitude might clash or complement Loki's trickster nature.
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 common theme is redemption. Since Loki has a complex and often villainous past in the main Marvel canon, in fanfictions about Kid Loki in the Young Avengers, there's often a focus on him trying to be a better person and earn the trust of the team. Another theme is friendship. How he forms bonds with the other Young Avengers members, like Kate Bishop or Teddy Altman, is often explored.
Thor would be a likely candidate. Since he is Loki's brother, he already has a connection with him. Thor might be the one to convince the other Avengers to give Loki a chance and be the first to reach out and try to befriend him in this new situation.
Future Loki might interact with the Avengers in a cautious way. He knows their past opinions of him and tries to prove himself. He could start by sharing small bits of useful information. For example, he might tell Iron Man about a weakness in a new enemy's technology.
The popularity of 'Avengers Young Loki Fanfic' might be due to Loki's popularity in general. He's a complex and interesting character. In these fanfics, seeing him as a young version adds a new layer of intrigue.
You can start by looking on fanfiction platforms like Archive of Our Own (AO3). There are often many tags related to Young Avengers and Kid Loki. Just search for those specific tags, and you'll be presented with a variety of fanfictions. Some might be focused on his character development, his relationships within the Young Avengers team, or his adventures in the Marvel universe as a younger version of Loki.
In this fanfiction, Loki might interact most with Hulk. It would be an interesting dynamic as Loki is a master of manipulation and Hulk is, well, the Hulk. Loki could either try to use Hulk for his own purposes, which would be very dangerous, or he could end up on the wrong side of Hulk's anger. But at the same time, it could also lead to some unexpected moments of understanding or at least a begrudging respect between them.
He would probably interact a lot with Thor. Since they are brothers, there is a pre - existing relationship full of complexity. Also, he might interact with Iron Man quite often. Tony Stark's sarcastic nature and Loki's trickery could lead to some really interesting exchanges, either in the form of verbal sparring or working together on some high - tech and magic - combined projects.