Hello! I've read your story, but I like it...so I'm going back to review because I've recently figured out as a new fanfic author that it's the polite and fun thing to do! ;)
It took me a bit to get used to the present tense in your writing since it's not the most common, but you keep it consistent, and it really works well. Good job!
I also had to comment that I loved this part:
"The boy's head jerks up from over his cauldron, and his eyes meet Snape's, wary and a little fearful.
Despite the fact that the first sixth year Potions class of the term is nearly over and no one in it has provided Snape a single excuse to take points from Gryffindor, the boy's look is enough to fill him with a warm, satisfied glow."
Hehe! I love that - fearful student eyes being Snape's key to happiness! Right on!
Author's Response: THIS MAKES ME SO HAPPY. Because I love "O Mine Enemy" so very very much, any approval from you is immensely valued.
And I'm glad you liked that line, I keep putting things into the story that make me laugh and I have to wonder if I have the world's strangest sense of humor or if anyone else is laughing with me...:)