The 'idle' state of the character also sets their initial emotion (sad, angry, etc). You can animate those idle states the same way you do for actions. However, the amount of emotion depends on where you have the Expressive slider in the characters Edit properties. You can't animate the amount, only the type of emotion. You could edit together scenes with the Expressive slider set to different levels to make it look like the character is smiling on demand, but it's tricky to match up (especially since 'Don't Breathe' doesn't work at the moment). Also, every time you create a character, their facial expression will be slightly different anyway, so I usually just keep copying and pasting the character until they have the appropriate expression on their mugs, then 'swap in' the correct expression while editing. Hope that is of some help