I liked this. Also, Emily Bronte's Wuthering Heights is another book I think was an influence. Heathcliff physically resembles and acts like Snape, to the point where it is very obvious. Of course, there are differences, especially as Heathcliff is the notable romantic gothic tragedy, but in a way, Snape could be too (if stretched).

That sort of rambled off of your essay, but I hope you see where I was coming from.