Common themes include the fall of Gotham. Without Batman to protect it, the city is at the mercy of criminals. There's also the theme of legacy. How Batman's death affects his allies and how they carry on his work or if they even can. And of course, the Joker's own twisted sense of accomplishment in finally killing Batman is often explored.
One common theme is chaos. With Batman gone, Gotham descends into utter chaos as the Joker runs amok. Another theme is revenge. Sometimes the story is about someone seeking revenge for Batman's death. Also, the exploration of the Joker's victory is a theme, showing how he relishes in finally killing his nemesis.
The main themes are often centered around the power vacuum in Gotham. Batman's death creates a huge void that the Joker tries to fill in his own deranged way. There's also the theme of despair among the citizens of Gotham. They've lost their protector, and the fanfiction might show how they struggle to cope. Additionally, the idea of the Joker's ultimate goal being achieved and what he does next is a big part of these fanfictions. He might try to prove that without Batman, the world is a much darker place, or he could just go on a wild spree of destruction for the pure joy of it.
The best chapter pointer here is Chapter 8, "Is He Shameless?". It opens with The resentment that had barely calmed among the crowd surged back two... and closes on Other people with a handsome and charming appearance often try to conceal....
Chapter 875, "Isn't That Xu Mei's View?", is the clearest early answer because it turns Jiang Buchen's situation into a concrete plot event. The chapter turns that into something concrete by moving from In the information network of the three people, Lu Yafei and Wan Jia...
If you want the clearest chapter reference, go to Chapter 15. Early on, Jiang Shixu woke up from those nightmares filled with blood and darkness,...; later, the chapter leans on The two sleeping pills he took in the evening had left him with a....
Chapter 868, "The Story of the Old Sea King Coming Ashore", is the clearest early answer because it turns Wen Jiaojiao's situation into a concrete plot event. A useful checkpoint is the way the scene starts with But despite Jiang Li saying so, the barrage in the livestream didn't...
A practical answer is Chapter 29, because it turns the idea into a concrete scene. The chapter opens with Big brother, it's me..." The shadow suddenly spoke and it was Jiang..., adds pressure through Learning from experience, Jiang Yan chose to stand next to Lin Manru this..., and ends on Big.
Chapter 903, "A Helicopter Came to the House?!", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. The chapter gives readers a real answer by opening on Jiang Buchen might barely meet the qualifications to enroll in the...
Chapter 844, ""Lang", is the clearest early answer because it turns Zhao Lang's situation into a concrete plot event. The chapter turns that into something concrete by moving from He had been married, but his wife disliked his disability and...
A practical answer is Chapter 29, because it turns the idea into a concrete scene. The chapter opens with Big brother, it's me..." The shadow suddenly spoke and it was Jiang..., adds pressure through Learning from experience, Jiang Yan chose to stand next to Lin Manru this..., and ends on Big.
If you want the clearest chapter reference, go to Chapter 16. Early on, Just as the words fell, Jiang Shixu swiftly cast his eyes downward.; later, the chapter leans on His eyelashes were very long; when they fell, they could cast a small....
Chapter 851, "Peace Charm", is the clearest early answer because it turns Gu Yu's situation into a concrete plot event. Early on, She initially came with the expectation of becoming the Gu Family's.... By the end, The Old Madam also looked at Jiang Li..