pekeleke

This chapter feels like a turning-point for Severus...

Petty? No. This is what being cunning and ambitious means. It has nothing to do with plotting to take over the world. It’s about getting back on your feet when everyone pushes you down. It’s about surviving long enough to have the last laugh. We, Slytherins, like to prove our points, and we despise giving up.
This is so well said. I always disliked the way the Slytherins were pictured in the books a whole house that's filled with nothing but bigoted, we-are-better-than-you, snotty, prejudiced, bad, and evil children and teenagers who do nothing but ridicule, hurt, and betray everyone around them. I never understood why an author would choose to portray every single one of them as being tainted in some way, and unlikable... These words you used, they seem to comprise the spirit of that house much more than whatever portrayal they received in the books.

Potter is kind. Genuinely, charmingly, kind. And Severus has the most terrible weakness for kind people. It’s what once drove him to Regulus. To Lily. And to Albus. It’s what keeps him coming back to Minerva, and what makes him put up with Hagrid’s ridiculous nonsense, even though he finds the giant’s tendency to ‘domesticate’ lethal creatures on the school’s grounds beyond frustrating. Kind people often break Severus’s heart, and he’s had more than enough of that already.
Aah. There it is. All those are people close to his heart. And Harry, just by being himself, has found the way there - if it weren't for Severus who has to try and push it closed in front of Harry's nose. But Harry is a Gryffindor. If the real hedge was not high enough to deter him, how could a metaphoric closed door ever be? ;)

He finds Potter’s kindness disarming, and it terrifies him. Severus doesn’t want Potter to become one of his terrible weaknesses. Potter isn’t a Slytherin, a cantankerous elder, or a child. Potter is heroic, attractive, straight. He is also madly in love with a motherly sort and twenty years Severus’s junior. Allowing himself to become—aware of the boy will only lead to disaster.
Yes, Severus, we know that you have a heart and that you want to guard it. But this is Harry - the kind (as you yourself have already established) wizard, who would be there to protect you. Why can't you just let him in? Hm? I mean, who cares about courting disaster, eh? It will be fine. Just try it. Yes? *nudge, wink*

This is what he wants: simple, easy, uncomplicated friendship. And he can have it. He just needs to be wary of the boy’s charming kindness, and that should be easy enough to do now that he’s identified it as a potential problem.
Severus! *bristles* No. No! Not that again! *rolls eyes*
Dear author, how many more chapters of completely unnecessary and equally fruitless as frustrating denial do we have to go through? And how many chapters did you say were in this story? Ah, my poor heart...