I love this kind of articles because it makes me feel like even though the story has ended, in a way it's still alive. J.K Rowling is explaining why Harry need his son after Snape through some tweets. And I love how fans demand this explanation because they are so interested on the story. Also I have a love/hate relationship with Snape, so it's always good to know more about him. The word I didn't understand was dichotomy. It means contradictory qualities. And she used this word to describe Snape.