Well, Gordon's reaction could be complex. On one hand, he might feel honored that Batman has chosen to disclose his identity to him. On the other hand, he could also be worried about the implications. Knowing Batman's identity means he has a greater responsibility to protect that secret. He might start to think about how this new knowledge will affect their working relationship and the safety of Gotham. For example, if the wrong people find out that he knows Batman's identity, it could put him and his family in danger.
Jim Gordon might initially be in disbelief. But then, considering all the times Batman has helped him and the city, he could come to accept it. He may also start to see Bruce Wayne in a whole new light, realizing that his playboy persona was just a cover for his nocturnal activities as Batman. He might even become more protective of Bruce's secret identity, as he knows how important Batman is for Gotham.
Batman would probably first try to contain the situation. He'd use his resources as Bruce Wayne to spread misinformation or counter the revelation. He might also go on the offensive against Scarecrow to stop him from spreading the news further.
One consequence could be that his enemies might target Gordon to get to him. Since Gordon now knows his identity, if the bad guys find out, they could use Gordon as a way to harm Batman.
Well, it might happen when Gordon stumbles upon some crucial evidence or has a moment of realization based on his long-term observations of Batman's actions and behavior.
Fanfiction explores their relationship in various ways. Some stories focus on the mentorship aspect, like how Batman trained Barbara to be Batgirl. For example, in 'The Mentor and the Protégé', it shows the early days of their relationship, with Batman teaching Barbara combat skills and detective work.
One great 'Batman Barbara Gordon Fanfiction' is 'Oracle Rising'. It really delves into Barbara's transformation into Oracle. It shows her strength and intelligence in a way that's both engaging and true to her character.
One more theme is the exploration of her dual identity. As Barbara Gordon, she is a librarian or a normal citizen, but as Batgirl/Oracle, she is a crime - fighter. Fanfictions play with this duality, showing how she balances her two lives. Sometimes she has to keep secrets from her friends and family, and this creates interesting plot twists and character dynamics.
You can try fanfiction websites like Archive of Our Own (AO3). It has a large collection of various fanfictions, including those related to Batman and Gordon. Just search for 'batman gordon slash' in the search bar and you'll likely find a good number of stories.
Batman is often portrayed as the brooding, dark vigilante. He's highly intelligent, with a strong sense of justice. He's dedicated to cleaning up Gotham but is also a loner at heart. Jim Gordon, on the other hand, is the honest cop. He's morally upright and willing to work with Batman despite the fact that Batman operates outside the law. He's a family man and is seen as the bridge between the law - abiding citizens and Batman.
The theme of sacrifice also comes up. Both characters are willing to sacrifice a lot for the safety of Gotham. In some fanfictions, they have to make tough choices that show their commitment to the greater good. For example, Gordon might risk his career to protect Batman's identity at times.