Koobazaur's Domain

When a player chooses a play style in a game, he is presented with a multitude of options. A “fighter” can use many weapons, parry, dodge, and use potions or magic scrolls. A “thief” can usually sneak around, hide in shadows, use sound cues, distract the enemy, turn off lights or use gadgets. Even in non-RPGs, such as a racing game, one can change their car, tweak the engine, ram into enemies or drive peacefully. And he can do it all dynamically, at any point in the game, constantly adjust and re-adjusting his strategy.
But a “conversationalist” – what can he do besides merely picking from one of the few predefined responses?