A comment on this story because I liked it a lot though I never got around to create an IJ.
I think Harry is a little too bubbly to be true to character here, but wow, I loved your Snape, wholly amoral and cold about it but endearingly so. And you wrote him wicked funny little lines. He's quite lucky Harry doesn't find out though, because he would have regretted it so much afterward, though methink Harry is less clueless here than he appears and that's why it can work between them in the first place.