Ok, kinda very loosely riffing on a B99 AU for SPN, detective AU but Sam's the only detective. He works for the precinct. He is Detective Winchester. Cas works in the morgue to do autopsies and stuff. He is Dr. Winchester because he married Dean and would rather use Winchester than have everyone say Winchester-Shurley every time. Dean works for the local fire department. He is Officer Winchester. Gabriel is a local lawyer who gives the rich people their just desserts when they try to take innocent people to court and is often around the precinct becayse Sam is. The other detectives love him bevause he brings sweets, sometimes shares, and is super funny. He is Mr. Winchester Esq.
There are two big things I see coming out of this.
#1:
When they're first hired on, everyone assumes Sam and Cas are biological siblings (bc Cas doesn't emphasize the hypen) and they never denied it when people called them brothers because they both figured "what's the point?"
Then comes the Christmas party, where they're introduced to Sam's brother, Dean. Cas comes in a little later and promptly gets a kiss on the lips from Dean.
The whole room freezes. No one knows what to do or how to ask until people start getting drunk. Eventually, Castiel's assistant, Meg, is slammed enough to ask "So are you two brothers or dating or what?"
Dean chokes on his drink and laughs til he can't breath but Cas is horrified and promptly makes an announcement to explain that he and Dean are, in fact, married and Sam is his brother-in-law not his biological brother.
From then on, they made sure to specify whenever relationships came up.
Funny thing #2:
Name confusion.
Imagine someone such as John Winchester is looking for, let just say, Sam and he knows he works in law enforcement so he goes to the precinct asking for Winchester.
John: I'm looking for Winchester
Secretary: Which one?
John: Excuse me?
Secretary: Which Winchester?
John: Sam.
Secretary: *sighs* Detective Winchester, Dr. Winchester, Officer Winchester, or Mr Winchester Esq?
John: ???
John: ...He was originally going to law school so I guess Esq?
The secretary then proceeds to give John the location of Gabriel's office. Upon seeing Gabriel, John asks him if he knows Sam. Being the chaos gremlin that he is, he tells John that he may be looking for Dr. Winchester over at the precinct. When John leaves, Gabriel calls Cas to inform him and Cas agrees to continue the chaos for once because he also doesn't like John but also promised Dean he wouldn't harm him.
John is sent down to Cas, who keeps his face hidden for as long as possible to keep him distracted before revealing himself. John doesn't know his face (because we all know this man didn't show up to Destiel's wedding) and asks with less patience if he knows Sam. Cas tells him he may be looking for Officer Winchester over at the fire station and John is clearly ready to loose it.
When John leaves, Cas calls Bobby, the fire chief, to inform him of John's visit and to keep an eye on Dean. John gets to the station, demanding to see Officer Winchester and Dean shows up. John practically blows up until Dean offers to take him to Sam. John agrees only because he knows Dean will know where Sam is and Dean only offers because he doesn't want Sam getting hurt by John when they eventually talk.
Upon arriving at the precinct, John and Dean find Sam, Cas, and Gabriel eating lunch together in the break room. This is when John looses it. He eventually gets arrested because he starts swinging when he finds out Sam is married to Gabriel.
So yeah, Detective/Law Enforcement AU?
Just for Funzies :)
