Pronouns take the place of proper nouns when context allows. However, it seems proper nouns are only ever conjugated in the third person, singular or plural. Is this a rule?
For example, if I'm talking directly to someone named Susan, I could ask her "Do you agree?" However, if I feel I need to specify who I'm specifically talking to, I could choose to by asking "Does Susan agree?". Is it grammatically incorrect to ask "Do Susan agree?"