There's 'Bobby and Crowley: An Unforeseen Alliance'. This fanfic is quite engaging as it starts with their mutual distrust but then slowly builds a connection between them. Also, 'The Surprising Friendship of Bobby and Crowley' is good. It focuses on how they, despite their differences, find common ground. A third option is 'Bobby x Crowley: A New Perspective' which gives a fresh take on their relationship, adding new elements to their characters and how they interact.
Well, 'Bobby's Encounter with Crowley' is a fanfic that you might like. It shows the first meeting between them from a different angle and how that initial encounter sets the tone for their future relationship. Then there's 'Crowley and Bobby: A Strange Pairing'. This one is interesting because it throws them into various situations that force them to work together and in the process, their relationship evolves. 'Bobby x Crowley: Unlikely Allies' is also a great read as it shows how they become allies in a world full of chaos and supernatural threats.
Another interesting one could be 'A New Understanding'. This fanfic could be about how they both learn from each other. Maybe Crowley teaches Bobby some demon lore that he didn't know, and Bobby in turn shows Crowley the value of loyalty among humans. It could involve a plot where they are both trying to save a small town from a new supernatural threat.
Fanfiction.net is also a place to check. It has been around for a long time and has a vast number of fanfics. However, the tagging system might not be as refined as AO3, so you may need to do a bit more digging. But it's still a good source for Crowley x Bobby fanfic.
Fanfiction.net is also a good place to look. There are many Supernatural - related fanfics on this site, and with a simple search for 'bobby x crowley', you might discover some great stories. However, the site's layout can be a bit old - fashioned compared to AO3.
One popular theme is the 'enemies to lovers' trope. Given their history in the show, it's interesting to see how they could go from adversaries to having romantic feelings for each other.
Another option is Tumblr. There are many fanfiction writers who post snippets or links to their Crowley x Bobby works on there. You can follow relevant tags like #CrowleyxBobby or #SupernaturalFanfiction to discover new stories.
There's also 'Crowley's Perspective'. It offers a unique take on their relationship by focusing mainly on Crowley's point of view. You get to see his internal thoughts and feelings about Aziraphale, which adds a whole new layer of depth to their relationship.
On Archive of Our Own, there are many great non - NSFW fanfics about aziraphale and crowley. You can search by tags like 'Good Omens', 'aziraphale/crowley', and filter for the appropriate rating. Some popular ones often explore their relationship in different scenarios, like dealing with a new threat in London while still maintaining their unique dynamic.
The idea of them protecting each other is also common. For example, Crowley saving Aziraphale from some angelic danger or vice versa. And then there's the theme of self - discovery. They both have been part of their own 'worlds' for so long, and in fanfics, they often discover new things about themselves through their relationship with the other. It's really interesting to see how different authors play with these themes.
One great fanfic could be about Crowley taking the reader on a tour of his favorite hidden spots in London. It shows his softer side as he shares parts of his world with the reader.
There's also 'In the Shadows of Twilight'. This fanfic focuses on a different aspect of their relationship, showing how they interact in a more secluded and mysterious setting. It's a great read if you like a touch of mystery in your fanfics.