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.
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.
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.
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.
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 could be a Bobby and Lisa fanfic set in a future world. They are part of a team that is trying to save the planet from an environmental disaster. Along the way, they face many difficulties and have to rely on each other's skills. This story would be both exciting and thought - provoking.
A Bobby Lisa fanfic could also revolve around a music competition. Both Bobby and Lisa are talented musicians, and they compete against each other at first but then realize they can create even better music by collaborating.
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.