confidant

(kŏnˈfĭ-dăntˌ, -däntˌ, kŏnˌfĭ-dăntˈ, -däntˈ)

1. One to whom secrets or private matters are disclosed.
2. A character in a drama or fiction, such as a trusted friend or servant, who serves as a device for revealing the inner thoughts or intentions of a main character.