I'm sorry you were late for work, but totally chuffed that you felt compelled to keep reading!
I want to hug this comment to me, first because what matters more to me than anything is getting the characterization right. I wanted Snape and Harry in particular to be vivid and complicated (partly because I detested the fact that all of Snape's actions in the series were reduced to one not-terribly-persuasive motivation). And second, because yes, exactly, Harry's been carrying that hatred around for years. And he's eminently capable of lashing out and doing harm - and not even recognizing the magnitude of what he's done. JKR's perfectly within her rights to portray him as Teflon Boy, someone who's neither touched nor changed by war and death and sacrifice. But I can't help feeling that he must be angry on some level, just as Snape is angry. And I was tired of Harry being passive. I wanted him to have enough self-knowledge to make the right choice, even when he didn't want to.
I'm so glad you enjoyed this and took the time to let me know!