Whats it mean when?

Whenever you speak to this person they try to treat you like you're lower life form. For instance speak in a condescending patronizing tone and talk down to you like you're a baby. Its almost forced. Not natural for a person to act this way and the exact opposite of the real cirstances. I would consider this person to be in a lower posiiton than I am and nothing special whatsoever yet they are talking down to me like they are superior, i'm stupid and an annoyance in just casual conversations.. What would cause that attitude and behavior?