Particulars

Out of a sudden, Hermione Granger is able to perfectly read Severus Snape's moods. How can that be? For the amazing Mersheeple, whose prompt I fell in love with: "Severus realised that depending on her mood, Hermione wears different coloured hair bands. She always seems to know what his mood is too... So what is HIS tell?" No betas, so any mistakes are my own!