Three friends are in the room. Two of them are having a conversation about the third. The third person can hear them but does not take part in the conversation. Come up with a reason that this person is not saying anything. Is it inappropriate for them to speak or are they physically restricted? Do the two friends know that the third is in the room?

This can be a dialogue for theatre or film or a scene in prose. Make sure the character who does not speak has some development in this scene. To simplify development, just make sure that at the start of the scene they feel a certain emotion and at the end they feel a different emotion, because of what has happened and in this case what has been said.