Character growth is also a key element. As the story progresses, they start to understand each other better. Maybe Loki learns to respect Hulk's simple and direct way of dealing with things, and Hulk starts to see that Loki has more to him than just being a villain. This growth often leads to a deeper connection between them.
One popular 'hulk x loki fanfic' is 'Unexpected Allies'. In this fic, Loki and Hulk find themselves in a situation where they have to work together against a common enemy. It's really interesting to see how their personalities clash and then gradually find common ground.
One great 'Hulk x Loki fanfiction' is 'The Unlikely Bond'. It shows an interesting dynamic between the two characters where they are forced to work together on a mission. Their clashing personalities create a lot of tension and some really humorous moments.
One possible character development for Loki is that he becomes more empathetic. Hulk's simple and straightforward emotions could rub off on Loki. He might start to feel genuine remorse for his past misdeeds. On Hulk's part, he could become more diplomatic. Working with Loki, who is a master of manipulation and politics in a way, Hulk could learn to use words as well as his fists to solve problems in the fanfiction.
You can try Archive of Our Own (AO3). It has a large collection of fanfictions, including many 'Hulk x Loki' ones. Just use the search function on the site and type in 'Hulk x Loki' and you'll get a list of relevant stories.
I'm not very familiar with this specific fanfic. However, generally, a fanfic about Loki and Thor might explore their complex relationship in the context of the Marvel universe. If Loki is intersex in this fanfic, it could add an interesting layer to the character's identity and how they interact with Thor.
It could be someone who is manipulating Loki to kidnap the Hulk. Maybe an even more powerful villain from the Marvel universe, like Thanos. He might be using Loki as a pawn to get the Hulk for his own evil purposes.
In Loki x Mobius fanfic, a common theme is the exploration of their friendship or a deeper emotional bond. Some fanfics may focus on their adventures together in different timelines. For example, they could be on a mission to fix a broken timeline, and during this, their relationship deepens as they rely on each other's skills. Loki's magic and Mobius' knowledge of the TVA are complementary in these stories.
Their relationship could be portrayed as a mentor - mentee one, where She - Hulk looks up to Hulk for his experience in dealing with his powers and the world of superheroes. Another way is to show them as rivals, competing to see who can save more people or defeat more villains in a given time. This would add a new dynamic to their interactions.
One interesting plot idea could be that Hulk and She - Hulk have to team up to fight a new super - villain who is immune to their individual powers. They must learn to combine their strengths in a new way. Another could be a story where they accidentally swap powers and have to deal with the consequences. For example, She - Hulk might struggle with Hulk's lack of control at times, while Hulk has to adjust to She - Hulk's more refined fighting style.