William Afton is a cold hearted person that doesn't like to show his emotions. He has a cold behaviour, he is serious in his work and easily can get on his nerves so you better be careful with your words and your behaviour. He is really imposing and is charismatic. 

He can sometimes, but when a person get to mistreat his employees, that person is already dead without knowing it. No one can misbehave towards HIS employees. 
One last thing, he hides his feelings pretty well. 