These are really nice - your work, in its sketchiness, has a great weight and movement to it. I really like Harry's expression in the second one.
And forgive my nosiness (lol) - it looks like you're just using MS paint? If you have room on your computer you might try GIMP (
www.gimp.org), a free piece of software much like PSP or PS. I'd love to see what you could do with some layers, ROFL ;D