I think a key factor is the character development. If the doctor undergoes significant changes or growth as they encounter the spn universe, that can make for a compelling story. Plus, creative use of the settings and conflicts from both the medical and supernatural aspects can draw readers in.
A really interesting plot could involve the Tesseract from the Avengers. It could be that the Tesseract has some sort of connection to the Darkness in SPN. When the Avengers are trying to protect the Tesseract, they accidentally release some of the Darkness. The Winchesters, with their knowledge of the supernatural, and the Avengers, with their superpowers, must then join forces to contain the Darkness again. The characters could also have some really fun interactions, like Dean being in awe of Iron Man's technology and Steve Rogers being impressed with Sam and Dean's hunting skills.
A great spn crossover fanfic often has well - blended universes. For example, if it's a crossover with Harry Potter, it should seamlessly integrate the magic of Hogwarts into the spn world. The characters from both should also be in - character. If Sam and Dean meet Harry, they should react in ways that are true to their personalities.
Sam Winchester and Bruce Banner would be an amazing pairing. Sam is highly intelligent and well - read, and Bruce is a brilliant scientist. They could bond over their knowledge and maybe even find a way to control the Hulk better. Also, Natasha Romanoff and Charlie Bradbury would be a cool pair. They're both strong, independent women with a lot of skills. Natasha could teach Charlie some combat moves, and Charlie could introduce Natasha to some cool geeky stuff like LARPing.
Sure. 'Supernatural and Sherlock' is an interesting spn crossover fanfic. It combines the mystery-solving elements of Sherlock with the supernatural world of Supernatural in a really engaging way.
A cool concept would be a joint mission. The Supernatural side has to deal with a powerful, ancient evil that has some connection to the vampire origin in the TVD world. So, they team up. Dean might be initially hesitant about working with vampires like Stefan and Damon, but they soon realize they need each other's skills to defeat this new threat.
Well, 'childish things spn fanfic' is special because it can explore the characters in a more light - hearted way. In normal Supernatural episodes, they face so much danger and darkness. But in these fanfics, they can have fun like normal people. They might play silly games or have a friendly competition, which is a refreshing change from the usual intense plotlines.
There could be unique character interactions and unexpected plot twists. Maybe seeing Doctor Who characters in a completely different fictional universe brings fresh and exciting dynamics.
For me, the charm lies in the blend of different story elements and the potential for new conflicts and resolutions that wouldn't happen in the original shows. It's like opening a door to a whole new world of possibilities.
There could be fun crossovers of powers and tech. Like Doctor Who's time travel capabilities combined with Marvel's superhero abilities.
The thing that makes it interesting is the way it blends the themes and settings of 'Doctor Who' with the elements from the other universe. It challenges our expectations and keeps us engaged throughout.