A really cool concept could be that there is a portal to another dimension opening up, and the supernatural law enforcers have to deal with all the strange and dangerous creatures coming through it. They need to figure out how to close the portal while also keeping the public safe from these unknown threats.
Perhaps a plot where a new law enforcement agent, who is half - human and half - werewolf, has to prove themselves in a world full of distrust towards their kind. They face challenges both from the supernatural criminals and from their own colleagues within the law enforcement.
One idea could be a story where a group of supernatural law enforcers have to stop a powerful vampire coven from taking over a city. They could use their unique powers like shape - shifting or magic spells to combat the vampires.
Show their growth over time. Maybe a young fairy law enforcer starts off being very naive and trusting. But as they face different challenges in the supernatural law enforcement world, they become more cynical and street - smart. By showing this development, your characters will seem more real to the readers.
One of the best is 'The Silence of the Lambs' by Thomas Harris. It has a brilliant portrayal of the FBI's hunt for a serial killer, with the complex character of Hannibal Lecter. Another great one is 'Gone Girl' by Gillian Flynn, which shows the investigation into a missing woman and all the twists and turns in the case. Also, 'The Girl with the Dragon Tattoo' by Stieg Larsson is excellent, with a journalist and a hacker investigating a decades - old mystery.
There was a situation where a law enforcement agency received reports of illegal logging in a protected forest area. The officers went deep into the forest, faced many difficulties like rough terrains and bad weather. They managed to catch the illegal loggers. Their determination to protect the environment through law enforcement was really inspiring. They also worked with environmental groups to ensure better protection of the forest in the future.
One of the best is 'The Protector' series. It has great character development. The male lead, a tough law enforcement officer, and the female lead, a strong - willed journalist, have a very engaging relationship that unfolds throughout the story.
Perhaps a fanfiction where a character from The Raid has some sort of special ability like the characters in Supernatural. Maybe he can see ghosts or has some sort of psychic power. This new ability could help him during the Raid and also change his relationship with his team members. He might be seen as an outcast at first but later prove to be very valuable.
One idea could be exploring the backstories of the different bloodlines in more detail. For example, you could focus on a particular family within a bloodline and how they've been affected by the supernatural elements over generations. Another idea is to create a new character who is a hybrid of two different bloodlines and show their struggle to fit in or their unique powers.
One idea could be a crossover where Goku from DBZ ends up in the Supernatural universe and has to team up with the Winchester brothers to fight demons. He could use his ki blasts against the hordes of hell.
Maybe a fanfiction where a bagel shop in the Supernatural universe is a front for a secret society of hunters. The bagels there are made with ingredients that can ward off demons, and the story could revolve around the main characters uncovering this mystery.
One idea could be a character suddenly gaining supernatural powers and having to learn to control them while also dealing with the regular Supernatural threats. For example, a hunter who gets the power to see the future and has to figure out how to use it to prevent disasters in the hunting world.
One idea could be exploring the relationship between the characters in more depth. For example, focusing on how Sam and Dean's bond was tested during that episode. Another idea is to create an alternate ending where things took a different turn.