What is the nature of the relationship between Emilia and Desdemona in act 4?

Which act?

Emilia is Desdemona's confidant and one of her women (possibly the only one to wait upon her). Desdemona asks Emilia's advice, and Emilia gives her what she asks for. Emilia acts for her husband in garnering the handkerchief, but she never knowingly hurts her.

Sorry...