This is gorgeous! The white highlights in their hair lead into each other beautifully, and their clothes and postures mirror each other really well; that, I think, sets off the contrasted expressions even more. (I second what albalark said about their postures, too--Minerva looks almost as if she's pulling away, her face turned toward the reader but her head is touching Severus's. Very conflicted, yet so intimate.)
Ah, yes, and the matching shoes. Everything's better with quirky--yet perfectly appropriate--shoes.