Nonono! Write more, I'm digging this version!
Very well. I'll see what else I can cook up.
This will be a direct continuation of what I posted above.
...
Just as she begins to think how all this doesn't make very much sense, she witnesses the attack on Snape's person, and with it, another emotion begins to surface: curiousity (and even a small bit of worry). Not at how easily Snape thwarted the attack, and not even on the attack itself, but at how calm, in control, and nonchalant Snape is at the whole thing, making her suspect that he was expecting such an attack. She deduces (this is if we were to assume that she really is as intelligent as the novels imply) that this incident must have correlated directly with his newly invented cure, and judging at the ease he showed, Snape must have known that creating and giving the cure to the Ministry would have attracted this kind of danger to himself, and prepared accordingly.
Sadly, due to the severed relationship between them, she can't exactly ask Snape what is happening, and so, day by day, her confusion and curiousity grows unabated.
Fast forward (either several weeks or months, I'm not sure, since it's up to you), her confusion and curiosity grows even more severe when she hears a rumor that the reason Snape has been leaving school ground ('on Ministry business', they always said whenever she asks) is because he had invented a spell that guards against the impossible, the Unbreakable Shield, and has been teaching it to the Auror Corps.
Later, when her shock finally dies down, she begins to ponder. What is he doing? Why would he create something that would severely reduce the danger posed by dark wizards? Because, Merlin, this could't have been something he did on a whim! Something on this scale would have required years, if not decades! It's something that should have been done by a whole government, not just one man! Furthermore, he should have known what kind of danger creating this spell would place him in! This won't just attract their attention; this would definitely place him in the blacklist of dark wizards all around the world! In fact, it can even be said that he's practically declared a war on them---!
As she ponders and ponders and ponders, an epiphany, in the form of a question, hits her like a brick.
...Was this the reason?
He called her a Mudblood, and thus, breaking their friendship. Not only that, he did so in public, sending a clear message to everyone that he (or rather,
she) had cut all ties.
Was this the reason?
Was it something he did deliberately, because he knew what kind of danger he would place himself, and the enemies he would surely gain in the future if he continues along this path? Because he knew that if he did this, it would paint a target not on just his head, but also those around him, and since she is a Muggleborn, she has no protection of a noble, or even a normal, wizarding family?
...Tell me, Severus, was this the reason?
...
Okay! I have no idea if this is any good, but feel free to use it any way you want!