I really like 'Crossroads of Krypton and the Hunting Life'. In this fanfiction, the writers did an amazing job of bringing in the mythology of Smallville and Supernatural. Dean and Sam Winchester end up in Smallville and get involved with Clark's world. It's full of action and some really cool character moments. It shows how the different powers and skills of the characters from both shows can work together or clash in interesting situations.
I really liked a fanfic called 'Power Convergence'. In this story, the Charmed Ones end up in Smallville and they have to figure out how to get back home. Along the way, they meet Clark and his friends. It's a great read because it shows how the different power dynamics from each show would play out when the two worlds collide.
The clash of different mythologies. Smallville has its Kryptonian and small - town - hero story, while Supernatural has demons, angels, and hunters. When these two collide in a fanfic, it creates a really unique and exciting world. For example, seeing how Clark's superpowers interact with the magic and weapons of the Winchester brothers.
One great Supernatural and NCIS crossover fanfiction is 'The Hunt in Quantico'. It combines the mystery-solving aspect of NCIS with the supernatural elements of Supernatural really well. The characters from both shows interact in a very believable way, and the plot keeps you on the edge of your seat.
A popular one is 'Crossing Paths'. This fanfiction has an interesting take on the crossover. It starts with a mystery that involves both the Supernatural and Buffy universes. The author does a great job of writing the characters true to their original personalities. Buffy's determination and the Winchesters' tough - guy attitudes are on full display, and the story builds up to a very satisfying climax.
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.
Well, there's 'Parallel Encounters'. In this fanfic, the settings of Supernatural and Tramiplier are merged in a really interesting way. It starts with a character from Tramiplier accidentally stumbling into the world of Supernatural. The story then unfolds as they try to find their way back while getting involved in the ongoing battles against demons and other evils in the Supernatural realm. It's full of action and some really cool character interactions.
One idea could be that the Winchesters end up in Smallville while hunting a demon that has some connection to LuthorCorp's experiments. Maybe the demon is using the kryptonite there for its evil deeds. Another could be that Clark Kent discovers the existence of the supernatural world through Sam and Dean. He could initially be skeptical but then realize there are threats that even his powers might not be enough to handle.
Definitely Clark Kent and Dean Winchester. Clark with his superpowers and strong moral code, and Dean with his tough - as - nails hunting skills and loyalty. They could have some great banter as they come from such different worlds but find common ground in protecting people. Another interesting pairing could be Sam Winchester and Chloe Sullivan. Sam's intelligence and knowledge of the supernatural could pair well with Chloe's investigative skills.
Some of the best Smallville and Stargate SG1 crossovers involve character interactions. For instance, Lex Luthor could get involved with the NID from Stargate SG1. This could create a whole new dynamic of power - hungry characters vying for control over alien technology. It makes for a really exciting read as the two universes collide in unexpected ways.
One great 'Fade Supernatural Fanfiction' is 'The Fading Shadows' which delves deep into the psychological aspects of the characters. It has a really engaging plot that keeps you hooked from start to finish. The author does an amazing job of building tension and exploring the complex relationships within the Supernatural universe.