They could both develop a stronger sense of sisterhood. As they face various challenges together, they might start to see each other as more than just fellow superheroes. They could support each other through personal issues as well. For instance, if Hawkgirl has some unresolved issues from her past life, Wonder Woman could be there to help her work through them and vice versa.
Friendship is a very common theme. Since they are both strong female characters in the DC universe, many fanfics explore how they become friends and support each other.
For Mega Man X, he could develop a deeper sense of empathy towards Quake Woman. Maybe at first, he doesn't understand her powers fully, but as they go on adventures together, he starts to respect and even admire her unique abilities. This could make him more open - minded in his future encounters with other characters with different powers.
Circe could be a great villain. She has powerful magic and could create all sorts of illusions and obstacles for Wonder Woman and Hawkgirl. She might try to turn them against each other or use their powers for her own dark purposes.
Perhaps they are in a competition within the Justice League to see who can complete a series of challenging missions first. This could lead to some friendly rivalry as well as them learning to respect each other's abilities more. Along the way, they might also have to deal with a villain who tries to take advantage of their competition.
There's also 'A Different Kind of Teamwork' that delves into how Hawkgirl and Wonder Woman form a unique bond. It shows their different perspectives coming together in a really interesting way. This fanfic explores their friendship and how they support each other during tough times in the DC universe.
Another plot could be a story where Hawkgirl and Wonder Woman have a misunderstanding at first. Hawkgirl thinks Wonder Woman is being too overbearing in her heroics. But then they realize they are more alike than different when they face a threat that targets female superheroes specifically. They then work together to take down the threat and in the process become good friends.
Both characters could develop their relationship in terms of trust. Naruto, who is generally trusting, could face some challenges that make him question Karin at first. Karin, on the other hand, could learn to be more open with Naruto. Their journey towards building a full - fledged trust could be the central theme of the fanfiction, with various events and conflicts testing and strengthening their bond.
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.
Wolverine could develop more patience. Usually a lone wolf, being around Nightcrawler's more upbeat and spiritual nature might force him to slow down and think more. For example, Nightcrawler's teleportation ability might make Wolverine rely on a different kind of strategy in combat rather than just his brute force.
In a Broly x Gohan fanfiction, Gohan could develop a new understanding of power. Instead of just relying on his academic knowledge and some of his traditional training, he could learn from Broly that power can also be about pure instinct. Meanwhile, Broly could develop his mental faculties. Gohan might introduce Broly to things like meditation or mental focus exercises. As a result, Broly becomes less of a mindless brute when it comes to fighting and more of a thinking fighter, which would be a significant character development for him.