In a crossover fanfic, the angels and demons from Supernatural could be involved in The Walking Dead universe. For example, an angel might be sent to Earth to stop the spread of the undead, believing it's part of a grand plan to save humanity. Meanwhile, the demons could be taking advantage of the chaos, making deals with desperate survivors. The Winchester brothers would have to navigate this new dynamic while also dealing with the walkers.
You can start by looking on fanfiction websites like Archive of Our Own (AO3) or FanFiction.net. These platforms have a vast collection of fan - created stories, and you can simply search for 'Walking Dead Supernatural crossover' in their search bars.
One idea could be that the Winchesters somehow end up in the world of The Walking Dead. They might use their hunting skills to fight the walkers in a different way than the survivors are used to. Maybe they try to find a supernatural cause behind the zombie apocalypse.
One popular trope is the characters from both shows teaming up to fight a common supernatural threat. For example, the Winchester brothers from Supernatural joining forces with Rick and his group from The Walking Dead to battle a horde of zombie - like demons.
One idea could be that the Winchester brothers from Supernatural end up in the world of The Walking Dead. They could use their hunting skills to fight off the walkers. Maybe they'd discover that the zombies are somehow related to a demonic presence and try to find a way to stop it.
One idea could be that the Winchesters find themselves in the world of The Walking Dead. They might use their hunting skills to deal with both the zombies and any supernatural elements that start to emerge in that world. For example, they could discover that a witch is causing the zombie apocalypse as part of a dark spell.
If Castiel were to be in this crossover, he would be very confused by the walkers at first. He's used to dealing with demons and angels, not undead creatures. But he would quickly adapt and use his angelic powers to protect the group. Rick from The Walking Dead would see Castiel as a valuable asset but also be a bit wary of his otherworldly nature. They would have to learn to trust each other as they both have the goal of protecting the survivors and finding a way to end the chaos in their respective worlds.
One great plot idea could be that the Winchesters from Supernatural find themselves in the world of The Walking Dead. They could use their hunting skills to fight off the walkers in a unique way. Maybe they think the walkers are some kind of supernatural creation at first and try to find a way to cure them like they do with monsters in their own world.
Michonne and Sam Winchester would be a great pairing too. Michonne is a skilled fighter with her katana, and Sam is very intelligent and well - read. They could work together to research any possible links between the walkers and the supernatural. Sam could also help Michonne come to terms with any new, otherworldly threats they encounter.
Dean Winchester and Daryl Dixon would make an amazing pairing. Dean's tough - guy attitude and his skills with weapons combined with Daryl's survival skills in a post - apocalyptic world would be really cool to see. They could go on zombie - hunting trips together while also sharing stories about their pasts.