Ooh, I'm always really impressed with watercolours, especially when they have so much lovely texture & depth to them like here.
Your Lupin reminds me of the work of one of my fave fanartists; and awww, look at him so busy studying and being serious despite the interruption. Bless.
And I can't help thinking that the troublemaker behind the bookshelves is actually Snape. But I don't mean that as a criticism; if anything it makes me love this piece even more!</i>