Often, there are plotlines involving her powers. If she has powers similar to Thor's lightning or Loki's illusions, she might train with the Avengers to better control them. This could lead to some interesting training scenes and character development. Also, there could be a plotline where she has to prove herself to the Avengers, as they are initially skeptical of her motives and abilities.
A common plotline is the Asgardian princess sister coming to Earth to seek help from the Avengers. Maybe Asgard is under some sort of threat, like a new powerful enemy has emerged, and she believes the Avengers can assist. Another plotline could be her being exiled from Asgard and finding a new home and purpose with the Avengers.
Some fanfictions might have a plotline where the Asgardian princess sister is a key to unlocking some ancient power or prophecy that is relevant to both Asgard and Earth. This would put her in a central role in the story, with the Avengers depending on her knowledge and abilities. There could also be a plotline about her trying to reconcile the differences between Asgardian and Earth cultures while being part of the Avengers.
One popular type of fanfiction in this category might involve the sister of Thor or Loki, who is a princess of Asgard, interacting with the Avengers. For example, she could be a powerful magic - user and help the Avengers in their battles against new threats. There are many fanfiction platforms like Archive of Our Own where you can search for such stories using relevant tags like 'Asgard princess' and 'Avengers' to find some great reads.
Another is the exploration of the relationships between the Avengers. For example, fanfictions might focus on the friendship between Tony Stark and Bruce Banner, or the romantic relationship between Natasha Romanoff and Clint Barton. These relationship - centered plotlines add more depth to the characters.
She could be a super - spy too, but on a different side initially. Maybe she was brainwashed by a shadowy organization. Natasha then has to fight her sister while also trying to bring her back to her senses. It would be a story full of action and emotional turmoil.
In fanfiction, if the Avengers go to Asgard, there could be a big clash at first. The Asgardians are proud warriors and the Avengers have their own ways. But then they might team up to face a common threat. For example, a powerful dark magic user could be targeting both Earth and Asgard. The Avengers with their diverse skills and the Asgardians with their magic and strength could form an unbeatable alliance.
One common theme is family. Since she's their sister, there's a focus on how she fits into the Avengers family. Another theme is acceptance. The sister often has to prove herself and be accepted by the other Avengers.
One common plotline is about the new generation living up to the reputations of their predecessors. They have to face challenges that test whether they can be as great as the original Avengers. Another is about them dealing with new threats that the old Avengers never faced. For example, new types of villains from different dimensions. Also, there are often plotlines about the relationships between the new heroes, like friendships and rivalries.
One possible story could be about how this Avenger, as the Princess of Asgard, uses her Asgardian powers and knowledge to help the Avengers in a battle against a powerful new enemy. For example, she might be able to call upon the Bifrost to quickly transport the team to different locations during the fight.
One reason could be that they see Loki as a victim of circumstances. Maybe they've come to understand that his actions were often influenced by forces beyond his control, like Thanos' manipulations. So they decide to defend him in Asgard.
Often, you'll see a plotline where Bella has some hidden power or ability that only becomes apparent when she meets the Avengers. This then cements the idea of them being soul mates. There are also plotlines where Bella is in danger, and the Avengers feel a strong urge to protect her because of the soul mate connection. And sometimes, it's about Bella helping the Avengers deal with their own personal issues because of this special bond.
One common plotline is Steve struggling with a mysterious illness while still trying to lead the Avengers. For example, he might be hiding his condition from his teammates because he doesn't want them to worry or think he's unfit for duty. Another could be that the illness is somehow related to a new enemy or a past mission. Maybe an experiment gone wrong during the super - soldier serum creation is starting to have side effects on him years later.