Mettaton hates being left out of the loop. He's a star--he's supposed to be at the centre of everything! But apparently, the drama and the action are happening while everyone is asleep. Considering he's never slept a wink for as long as he's existed, the chances of him getting in on that action are, in fact, zero.

Anyone running into him around bedtime will find him in a rather grumpy mood. Being a ghost in a robot's body can be a real drag sometimes.