I’ve been thinking of stories that involve protocol breaks or invisible protocols. For example the case studies/anecdotes in Geoff Manaugh’s Burglars guide to the city are all about how burglars/thiefs see the protocol of a city differently compared to people who inhabit it. The challenge would be to show the exposition of these without it sounding like its forced
The detective itself would borrow from bureacratic heroism - someone who is unremarkable, easily blends into situations. Columbo is an example for this type of detective.
I guess the above ideas do fall into the category of protocol forward procedurals.