I read a fic many moons ago, didn't bookmark it and would really appreciate any help to find it again.  Here is what I remember of the plot...

It starts off with John and Sam fighting.  The argument starts to turn from verbal to physical, Dean steps in to separate them and John accidentally hits Dean.  Possessive!Sam comes out and John leaves the motel room to sit in a lounge chair by the pool where he can still see the boys through the window...and things get smutty from there.  

Thanks again if anyone remembers it.

ETA:  FOUND!!! this community and its members totally rock!  See comments for story link : )