Bruce Wayne has been depicted as having a sister in certain comic iterations. For example, in some versions, a character named Martha Wayne Jr. is introduced as his sister. However, this isn't a consistent element throughout all Batman comics.
One interesting fanfiction could be where Bruce Wayne's little sister discovers his secret identity early on and has to keep it a secret herself while also trying to help him from the shadows. Maybe she uses her own unique skills, like being a computer genius or having a talent for martial arts.
Often, she is depicted as being just as intelligent as the male Bruce Wayne. For example, she has a sharp mind for detective work and strategy. She might be able to quickly analyze crime scenes and figure out the motives of the villains.
Sure. In the comics, Bruce Wayne is known for being a playboy. This fa莽ade allows him to blend in with high society while secretly fighting crime as Batman.
He might develop a greater sense of humility. Without the Batman persona to fall back on, he has to face his own limitations as a person. For example, he may struggle to get people to listen to his ideas for change when he doesn't have the intimidation factor of Batman.
Another aspect could be that in some darker fanfics, if Bruce Wayne were to cross a moral line, perhaps Alfred would have to take more extreme measures. He might cut off Bruce's financial resources related to his vigilante activities. This would force Bruce to re - evaluate his actions and the way he operates as Batman. It's a way of punishing him to make him understand the importance of ethics even in his fight against crime.
Bruce Wayne is super rich in comics. His wealth is vast and comes from multiple successful businesses and inheritances. This enables him to have all the resources needed for his crime-fighting and to support Gotham City in various ways.