I just thought of an interesting case:
In Dragon Quest 3, ordinarily the main character (who is, perhaps, intended to be the player's avatar; this is espeically apparent in the remakes which start with a personality quiz much like Ultima 4-6) does not talk. However, there is one instance where, to enter a certain dungeon, one character needs to go in alone, and that character is always the first (living) character in the lineup. When you return from the dungeon, the rest of the party will be waiting, with the second party member at the front, and to leave, you have to talk to said second character. If that character is the protagonist, then the game will have the protagonist talk for one line. What do you think of this case?
(By the way, after beating the game you can remove the main character from the party. Try beating the game and see what happens during the ending!)