One common theme is the exploration of their power dynamics. Given Valkyrie's warrior - like abilities and Bruce's, well, his own set of skills, how they interact in different situations is often explored.
One common theme is friendship. Given their strong and independent personalities, fanfics often explore how they become friends and support each other. For example, they might start off as rivals but gradually learn to respect and rely on one another.
Forgiveness is also a big theme. Bruce may have to forgive Jason for his actions, and vice versa. There's also the theme of trust. Since their relationship has been through so much turmoil, rebuilding trust is a central part of many stories. For example, in some fanfics, they start out not trusting each other at all, but as the story unfolds, they learn to trust again.
One common theme is the exploration of their mutual understanding. Given their complex pasts, fanfics often show how they can see through each other's facades. For example, in many stories, Natasha is able to calm Bruce when he's on the verge of losing control.
One common theme is the struggle between good and evil. Bruce represents good and Jerome represents evil, and their relationship often explores how these two opposing forces interact. Another theme is obsession. Jerome is often depicted as being obsessed with Bruce in some way, whether it's his power or just his presence in Gotham.
Sure. You can start by looking on popular fanfic websites like Archive of Our Own. Just search for 'Valkyrie x Bruce' in their search bar and you'll likely find a variety of stories written by different authors. Some might be adventure - themed, where Valkyrie and Bruce go on some epic quests together.
Love in the face of chaos is a big theme. Gotham is a dangerous place, but Selina and Bruce's love manages to thrive. Also, the idea of two outcasts finding solace in each other. They are both different from the ordinary people in Gotham, and their relationship is a form of connection in a city that can be very isolating. And secrecy is often a theme too, as they have to keep their relationship hidden from many in Gotham.
Since Bruce is often associated with heroism in many contexts, one common theme might be the futa character being inspired by Bruce's heroic deeds and then a relationship budding from there. Another could be the exploration of their different personalities and how they complement or clash with each other, leading to an interesting dynamic in the fanfic.
One common theme is the battle of ideologies. Bruce Wayne stands for a world of rules and order, while the Joker wants to disrupt it all. Another theme could be redemption, where either character might be on a path to change. Also, the theme of obsession is often present, as the Joker is obsessed with Batman and vice versa.
There are also fanfics that focus on the scientific aspect. Since Bruce is a scientist, the reader might be his assistant or a fellow scientist, and they explore scientific mysteries together while their relationship grows on the side.
There's also the theme of secrecy. Bruce has to keep his identity as Batman a secret, and this creates a lot of tension in the relationship. The reader may suspect something or eventually find out. A lot of fanfics play around with this idea. Also, redemption is sometimes a theme. The reader might be a character who helps Bruce find more balance in his life, between his playboy persona and his role as a vigilante.