A character from a fictional video game or book, who does not directly and vocally interacts with others. They still talk, only, we cannot HEAR/READ what they say, but other characters do. Sometimes, you can actually read or hear their thoughts. While silently interacting, they move their body, such as nodding, or bowing their heads.
Isaac from Golden Sun, Crono from Chrono Trigger, Serge from Chrono Cross, Ryu from Breath of Fire 1/2/3/4, etc.