"Just an Example, put together for a questioner on the Forum for Fallout 4 - this is a few examples of how 'Companions can smile at the Player'. It appears to be connected to the Affinity ranks [how much the Companion likes you - they might need to be 'maxed out', I am not 100% on that yet]. Their visage also changes based on what they are talking about at the time (eg. they will look sad when talking about something sad). There was someone who specifically asked for an Example from a game with no Game Mods, since they were not seeing it in-game themselves; I'm only running SweetFX in ReShade here, no Game Mods at this time . HTH ~T"