A cool plot could be a time - travel crossover. The 'Supernatural' crew travels to a time when Star City was in its early days. They meet a young Oliver Queen and end up changing some events that have a ripple effect on both their universes. This could lead to new alliances and new enemies. Also, a powerful witch from 'Supernatural' could put a spell on Star City that only the combined efforts of the two groups can break.
Sam and Oliver would probably start off a bit cautious with each other. Sam, being the more cerebral of the Winchesters, would be interested in Oliver's methods of protecting the city. Oliver, on the other hand, might be a bit skeptical of Sam's supernatural knowledge at first. Dean would likely bond with Diggle over their combat skills. They'd probably exchange stories about their battles, and Dean might even show Diggle some of his unique ways of taking down enemies. Castiel, with his angelic powers, would be a mystery to the 'Arrow' characters. Felicity might be both intrigued and a bit scared of him, but she'd also be eager to understand how his powers work.
One great 'Supernatural' and 'Arrow' crossover fanfiction is 'The Hunt in Starling City'. It combines the dark, supernatural elements of 'Supernatural' with the gritty, urban setting of 'Arrow'. The story has Dean and Sam Winchester arriving in Starling City to hunt a demon that's been causing chaos in the criminal underworld, which draws the attention of Oliver Queen and his team. They initially clash but then realize they need to work together to stop the greater evil.
A cross - over could involve a curse in the 'Arrow' world that has a supernatural origin. Oliver Queen and his team seek the help of Sam and Dean Winchester who are experts in dealing with the supernatural. Along the way, there are clashes in their methods of operation but they gradually learn to trust each other and combine their skills to break the curse.
Oliver Queen and Dean Winchester would be an interesting pairing. Oliver is used to leading a team and taking on tough enemies in his city. Dean is a no - nonsense hunter. They could have some great banter and learn from each other's combat and survival skills.
One common theme is the clash of two different worlds. Arrow is mainly about a city full of crime and vigilantes, while Supernatural is all about the supernatural world. So, when they cross over, there's often a struggle to understand each other's ways. For example, Oliver might be skeptical of the existence of demons at first, while Sam and Dean might not be used to dealing with high - tech security systems in Star City.
Well, it's about the characters. Both shows have a great set of characters. 'Supernatural' has the complex and lovable Winchester brothers, and 'Arrow' has Oliver Queen with his own set of friends and enemies. In crossover fanfiction, these characters can interact in ways that are not possible in their original shows. Imagine Dean Winchester teaching Oliver Queen some of his hunting skills, or Felicity Smoak helping Sam Winchester with some tech - related supernatural mystery. It's these kinds of interactions that make it appealing.
A good plot is key. It should blend the elements of both Arrow and Supernatural in a seamless way. For example, it could have the characters from Arrow dealing with supernatural threats like the ones in Supernatural.
One great Arrow Supernatural crossover fanfiction is 'The Hunters and the Hood'. It has an exciting plot where the characters from both shows team up to fight a common supernatural threat in Star City. The way the author combines the gritty, crime - fighting world of Arrow with the spooky, otherworldly elements of Supernatural is really engaging.
One idea could be that the characters from Arrow get transported to the Supernatural universe. Oliver Queen could team up with the Winchesters to hunt a demon that has somehow made its way into Star City. Maybe the demon is using some of the technology in Star City to create chaos, and they have to combine their skills - Oliver's archery and combat skills with the Winchesters' knowledge of the supernatural - to stop it.