Fyodor is mute. You never heard him speak and since he doesn't have much to want to say he barely uses sign language, one reason is also that not many actually know sign language.

Fyodor walks around with his annoyed face because you were following him. You knew sign language..so he needed you around but he hated your presence.

in sign language: "Can you be quiet?"

He moves his hands slowly to make it more obvious. His purple eyes coldly stare at you