Another great storyline could involve the prophecies in Good Omens intersecting with the apocalyptic events in Supernatural. The characters from both would then be scrambling to prevent or at least manage the impending doom. The Horsemen from Supernatural might interact with the Horsemen - like figures in Good Omens, leading to a battle of wills and powers that would keep readers on the edge of their seats.
One idea could be that Crowley from 'Good Omens' and Lucifer from 'Lucifer' meet in a neutral realm. They start off as rivals, each thinking they are the most devilish. But as they interact, they realize they have more in common than they thought. Maybe they team up to play a prank on some self - righteous angels, which goes awry in hilarious ways.
One interesting storyline could be the interaction between the angels and demons from Good Omens and Lucifer. Maybe the characters from Good Omens end up in Lucifer's LA and have to deal with his brand of chaos. It could lead to some really funny and thought - provoking situations as they compare their different views on good and evil.
Another idea is that the Avengers' time - traveling adventures somehow cross paths with Good Omens' apocalyptic timeline. The Avengers could accidentally end up in the middle of the Good Omens' end - of - the - world scenario. They might try to use their technology and powers to stop the apocalypse in the Good Omens universe, while Aziraphale and Crowley are both amused and a bit confused by these new, powerful visitors.
One way to create an engaging plot for this crossover fanfiction is to focus on the characters' reactions to the new world they find themselves in. Imagine Dean Winchester suddenly in the middle of London and being confronted by an angel and a demon who don't quite act like the ones he's used to from his own world. His confusion and initial mistrust could lead to some interesting dialogue and action scenes. Sam, on the other hand, might be more open - minded and start asking questions about the Good Omens universe. Meanwhile, Aziraphale and Crowley are trying to figure out who these strange American hunters are. This interplay between the characters from different universes can drive the plot forward.
Castiel's stoic and somewhat naïve personality in Supernatural would contrast with the more worldly and sly characters in Good Omens. However, his loyalty and sense of duty could be something that the Good Omens characters would admire. And in return, the Good Omens crew could teach Castiel to loosen up a bit and not be so rigid in his thinking.
One plot idea could be that Aziraphale and Crowley from Good Omens get dragged into a case that the Winchester brothers are investigating in Supernatural. Maybe it's a demon that's a bit too powerful for Sam and Dean, and they need the help of the angel and demon duo who have a different approach to dealing with the supernatural. Another idea is that the two universes' versions of Heaven and Hell start to merge, and characters from both shows have to figure out how to stop it while also dealing with their own personal issues.
I think Loki and Crowley would be quite the unlikely allies. Loki is known for his trickery and self - serving nature in the Avengers universe, and Crowley from Good Omens is also a demon who loves to cause a bit of chaos. They could team up to play pranks on both the Avengers and the forces of Heaven and Hell from Good Omens. Maybe they'd create illusions to mislead everyone and have a good laugh while doing it.
One interesting pairing could be Dean Winchester and Crowley. Dean has a lot of experience dealing with demons in the Supernatural world, and Crowley has his own unique charm and deviousness. Their interactions would be full of witty banter and power plays. Another pairing could be Sam Winchester and Aziraphale. Sam is the more intellectual of the Winchester brothers, and Aziraphale is an angel with a vast knowledge of the cosmos. They could have deep conversations about morality and the nature of good and evil.