Google-fu and searching through AO3 has failed me, so I've apparently NOT bookmarked this fic. I'm searching for a story where Jared is a bored medical professional (doctor, etc.) - through secret experimentation on people he is able to give clients what they want in terms of kinks. He decides to create a perfect human bitch and posts an ad - Jensen is a college student and applies for the position. I remember Jared inviting Jensen to this house (i.e. home base) and telling Jensen he'd have time to do his school work. Jensen falls asleep and Jared injects some sort of solution into him to start the process, and Jensen wakes up to Harley (I believe that's the name of the dog) in bed with him. The staff help cover up (i.e. sleeping drugs in food) but are paid to keep their mouths shut. Last I remember this was still a work in progress. I can't remember if it was Jared/Jensen because I think there were only two chapters when I read it last.