Perhaps a crossover where Scooby and Shaggy end up in a post - apocalyptic world. They have to rely on their survival skills, which they've developed from all their mystery - solving adventures. They could meet new characters who are tough survivors but lack their unique sense of humor and ability to find food in the most unlikely places. Together, they work to uncover the mystery of what caused the apocalypse.
To make it stand out, focus on the unique relationship between Scooby and Shaggy. Their friendship and how they support each other through scary situations can be explored in depth. Also, create new and interesting villains or mysteries that are different from the usual Scooby Doo plotlines.
In a fanfiction crossover, Ghost Rider could end up in the Mystery Machine by accident. His flaming skull would surely freak out the gang. However, he might need their help to track down a villain who has escaped into the world that Scooby Doo and his friends inhabit. They could combine their skills, with Ghost Rider's supernatural powers and the gang's mystery - solving abilities.
There is a fanfiction titled 'Scooby and Shaggy's Time - Travel Tale'. In this story, they accidentally travel through time while chasing a mystery - making villain. As they journey through different eras, they face new challenges and learn more about their friendship. Also, 'The Mysterious Island with Scooby and Shaggy' is a fanfic that takes them to an uncharted island full of strange creatures and secrets.
Well, perhaps the plot involves a female Shaggy who has a special connection to one of the villains. Maybe she knew the villain from her past and this knowledge helps the gang understand the motives behind the spooky happenings. She could also use her charm and wits to get closer to the truth than the others in the group. As the story progresses, her relationship with the other characters, like Fred, Velma, and Daphne, might evolve in interesting ways as they all work together to solve the mystery.
A Scooby Doo and Harry Potter crossover fanfic would be cool. The gang could go to Hogwarts for a school trip and end up having to solve a mystery involving a poltergeist that's scaring students. They'd have to use both their detective skills and some magic knowledge they pick up along the way. Shaggy and Scooby would probably be really excited about all the food in the Great Hall.
Definitely Scooby - Doo. They have a special bond. Besides, Fred might join in. Fred is good at building traps, which could be useful in the 'war' situation. Daphne could also be there. She has a lot of courage and could support Shaggy when he's in a tough spot.
A cool concept could be a possession story. A powerful supernatural entity tries to possess members of both groups. Scooby Doo and the Mystery Skulls have to find a way to stop it before it's too late. This would bring out different reactions from the characters. Scooby and Shaggy might be more panicked, while the Mystery Skulls, with their prior experience, would be more strategic in their approach.
Well, perhaps there could be a crossover where Scooby and Shaggy accidentally eat some magic cupcakes in Equestria that give them the ability to talk to the ponies in a special way. Then they discover that there is a mystery surrounding a disappearing magical element in Equestria. The rest of the Mystery Inc. gang shows up to help, and they all join forces with the ponies like Rainbow Dash and Fluttershy to find out what's going on and save the day.
One idea could be that the Winchester brothers are hunting a ghost in a town where the Mystery Machine gang also happens to be. The Scooby gang initially mistakes the Winchesters for bad guys but then realizes they're all after the same spooky entity. They could team up, with Sam using his research skills and Dean showing the Scooby gang how to handle real weapons (in a non - dangerous way, of course).
Well, a very common theme is the comical situations that can arise from Shaggy loving Daphne. Given Shaggy's laid - back and often scared personality, his love for the more confident and glamorous Daphne can lead to some really funny moments. Another theme is the internal struggle within Shaggy. He has to balance his love for Daphne with his loyalty to the group and his friendship with the others. And sometimes, the theme of a hidden relationship might come up, where Shaggy and Daphne try to keep their relationship a secret from the rest of the gang.