There are quite a few interesting Bruce Banner fanfics. For example, 'Bruce Banner: The Man Behind the Monster' really digs into who Bruce is as a person, not just the Hulk. It shows his intelligence, his kindness, and his constant fight against the beast within. 'Hulk's Impact on Bruce' is another one. This fanfic details how the existence of the Hulk has changed Bruce's life in every aspect, from his relationships to his view of himself. And 'A Day in the Life of Bruce Banner' gives a very realistic portrayal of what a normal day might be like for him, with all the challenges of living with the Hulk.
One great Bruce Banner father fanfic could be 'A Father's Redemption'. In this fanfic, Bruce tries to use his scientific knowledge to protect his family from his own Hulk alter - ego. Another is 'Banner's Fatherly Love' which focuses on how he teaches his child to accept differences. And 'The Father Bruce Banner Always Wanted to Be' shows his journey in becoming a better father figure through various challenges.
There are fanfictions that explore Bruce Banner's relationships, like his friendship with other Avengers. For example, a story could focus on how he and Tony Stark collaborate on a scientific project while also dealing with their differences, which is really engaging as it combines both their characters' traits well.
One possible story could be about how Bruce Banner's scientific mind deals with the physical and emotional changes during the pregnancy. Maybe he tries to use his knowledge to understand the unique biological processes at work.
You can try Archive of Our Own (AO3). It has a large collection of fanfics including many about Bruce Banner. Fanfiction.net is also a good place. There are often some great stories there.
One common theme is the exploration of their intellectual connection. Since both characters are brilliant in their own ways in the original Marvel universe, fanfics often delve into how their minds interact when one of them is female. Another theme could be the relationship development, from initial acquaintance to something more romantic or platonic.
The appeal of 'Bruce Banner x Tony Stark' fanfics lies in their contrast. Bruce is the calm, introverted scientist, while Tony is the flamboyant, extroverted genius. Their different personalities create interesting dynamics. For example, in many fanfics, Tony's brashness can both annoy and amuse Bruce. And Bruce's stability can ground Tony. This contrast leads to great character development and relationship - building in the stories.
Another plot could be that Bruce Banner is doing some research on a new form of energy and it somehow links to Harry's magic. Harry is brought in to help understand this strange new energy which has properties similar to magic. In the process, they learn from each other's worlds and develop a friendship while trying to keep this discovery from falling into the wrong hands.
A great plot twist could be that Bruce's Hulk side has some sort of hidden knowledge or ability that even he wasn't aware of. For instance, the Hulk might be able to communicate with an otherworldly being that can help them defeat a powerful enemy they were previously losing to. This would completely change the dynamic of the story.
One interesting concept could be a crossover where the magic of the Harry Potter world interacts with Bruce Banner's scientific knowledge. Maybe Banner could be intrigued by the potions in the wizarding world and try to analyze them with his scientific mind. Another concept might be a situation where the Hulk's strength is pitted against the powerful magic spells of Harry Potter characters.
The clash of two very different worlds. Harry comes from a world of magic and Bruce from a world of science. When combined in fanfiction, it creates a unique dynamic. Writers can play with how their different ways of thinking and problem - solving interact.