I am answering the question related to your examples (NOT 'being the one who") "the one who" or "the ones who" subject is (the one who) does something. Plural subject are (the ones who) do something. It is not used more for a negative thing. I could say: Tom: You're so helpful. Jack: No, you're the one who's been so helpful!! --------------- 'the one who" is a replacement for "the person who" "the ones who" replaces "the people who" Our office manager Mary is the person who knows the answer to the question. BECOMES >>>> Our office manager Mary is (would be) the one who knows the answer to that question. --------------- Married women are usually the ones in a marriage who do the most housework.

You are the one that/who is being deceiving. (In this moment or recently)