I had a similar experience with my current employer, I gradually worked up from a position in the warehouse (general dogs body) to a position where I directly reported to a middle management type guy.
He (and others) treat me very differently to those that had been employed directly (from outside) who IMHO were not half as good at there jobs as I was.
I eventually left to go self employed which didn't work out (drink) then a job came up at my old/current employer (a slightly higher position)
As I knew what it was like before I changed the way I interacted with everyone, basically I took the view that this was a job with colleagues not friends (as I knew them all) an I treat them as such, respect everyone and be professional at all times, I don't even get into discussions on personal lives ect with them
All I can say is do your job do it well and forget about this guy who is obviously a dick, eventually he will treat u like you should be, or people will begin to notice that he does not.
All the best
AoS