I think, if they really want to sprinkle expressions here and there, they could tie them to dialogue choices. Something like, if you're chill about Raphael's teleportating thing then you're also chill about the reveal rather than looking absolutely flabbergasted.
For the whole smirky thing going when talking to companions i'd just go with a set personality, and maybe it could be something we can swap at will too since it'd just amount to a stance.
