HBP spoilers: teensy afterthoughts, probably the first of many; this one as a non-lover of Snape. This will be of no interest to the people who love him already.
My WTF??, world-turned-upside-down moment, when I finally *got* Snape:
'... Not all wizards can do this, of course; it is a question of concentration and mind power which some,' his gaze lingered maliciously upon Harry once more, 'lack.' (UK edn, p 170)
This, of course, in their first DADA lesson after Malfoy had petrified Harry on the train, and Harry hadn't been able to perform magic silently.
I'll never love Snape; I had too many overbearing and bullying teachers at school, and know what it's like to feel powerless in the face of that.
And to my mind, much of the active Snape-love I've seen still remains on a par of incomprehensibilty to that of befriending and marrying men who are in prison.
But this passage was an epiphany. There really is more to Snape (potentially) than the typical bullying teacher.
(I'll never call him Severus, though. I don't think he'd appreciate it, for one thing.)
And Regulus, Regulus! How I love you. That note had all the 'Fuck you!' aplomb of your brother. You really make me want to finish that Black Brothers fic.