People of all sorts.

One of my clients is going on maternity leave. This other lady took over, and she's just downright...

I'm not your subordinate, I don't report to you, you don't pay me, neither do you pay for our services, so don't speak to me as if I'm working for you. I'm working with you.

Stop trying to assert your authority. We don't have to do what you want. Adapt to us, not we adapt to you, so F off.