How do you actually get to talk to Ei instead of the Shogun puppet?

Sorry if this is a basic question. The opening has the Shogun talking about being my guard and not showing much personality — cold, formal, exactly as described. But the character is supposed to have Ei underneath who's supposed to be way more expressive. Is there something specific you say or ask to get the switch to happen, or does it just happen on its own over time? I don't want to force it in a way that feels out of character for either of them.