Maybe in a fanfic, Finn's death could be part of a time - traveling accident. He could get caught in a time rift while trying to save someone or something important. His death would then cause a chain reaction in the timeline of Adventure Time. The fanfic could focus on how the other characters try to fix the timeline to bring Finn back or at least come to terms with his loss.
Jake would be devastated. He and Finn are best friends. Jake might become withdrawn and less likely to go on adventures. He could also become overprotective of Finn's memory. Princess Bubblegum would likely be deeply affected too. She might feel guilty if she couldn't use her scientific knowledge to save Finn. She could also be motivated to find a way to bring him back. Marceline would probably be very sad and angry. Her relationship with Finn was special, and his death could make her more cynical about the world.
One popular story might be one that focuses on how the other characters in 'Glee' deal with Finn's death on an emotional level. They could be struggling to come to terms with the loss and how it affects their performances and relationships within the glee club.
I'm not entirely sure as I haven't read it specifically. But generally, it might be about a battle or conflict between the character Dredd and the concept of death. It could involve Dredd facing death - like challenges, maybe some high - stakes showdowns with death - related entities or situations.
Some write them to explore the darker and more emotional aspects of the Adventure Time universe. Finn is a beloved character, and his death can bring out strong emotions in both the writer and the reader.
Some fanfictions might show the characters crying a lot and being unable to focus on their normal activities like singing in the glee club. They could be constantly thinking about Finn and having flashbacks to their memories with him.
This type of fanfiction is quite heavy. It could depict Rachel's downward spiral leading to her suicide, perhaps due to the overwhelming grief of Finn's death. The writers of such fanfictions might focus on how the other members of the Glee club try to hold on to their own sanity while also dealing with the loss of two important people. It can be a very emotional read, full of heartbreak and a sense of hopelessness at times.
Since I haven't read it, I can only assume that Dredd is one of the main characters as it's in the title. There might be other characters like his allies in the law enforcement or the antagonists who are related to the 'death' aspect in the story.
One idea could be exploring how the other characters like Jake deal with Finn's death. Maybe Jake would go into a deep depression at first, as they were such close friends. He might then try to find a way to bring Finn back, leading to all sorts of magical and dangerous adventures.