The 'Kiss of Death' fanfiction could also focus on character development. For example, it could show how a character reacts to a life - threatening situation or a complex emotional encounter. Maybe Finn or Jake are faced with a new kind of enemy or a moral dilemma related to this 'kiss of death' concept, which changes them in some way.
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.
It might be interesting because it gives fans a chance to see their favorite characters in a different light. Maybe Princess Bubblegum is involved in a 'kiss of death' scenario that reveals a more vulnerable side of her or shows a different aspect of her relationship with other characters like Marceline.
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.
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.
In the original series, Finn is alive and has all his adventures. But in the fanfiction about his death, the whole tone is much darker. The original is full of light - hearted moments, while the fanfiction is likely to be more solemn and sad.
Finn might initially go into denial. He could keep expecting Jake to just pop back up like he always does. Then he'd probably get angry, at himself or at whatever caused Jake's death. Eventually, he'd start to accept it and try to honor Jake's memory by being a better hero.
The first time in fanfiction can vary greatly. Some fanfictions may portray it as a spontaneous moment full of passion. Others might show it as a more hesitant and gentle encounter. It depends on how the author wants to develop their characters. If the fanfiction is set in a particular storyline where they are facing challenges, this moment could also be a form of escapism for them within the story.
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.
I'm not familiar with a character named Bronwyn in Adventure Time. It could be a very minor character or a name that is not part of the mainstream Adventure Time canon.