Snack! It's been forever since I read a deliciously long and good Snack. The way their "association" develops is wonderfully believable -bit by bit, conversation by conversation, incident by incident. Snape's jealousy of how Potter manages to get through to Draco while he gets nowhere is so him, and so very hilarious. Loved Remus' cameos as well. Also, hotness.
And A+ for a story where the adults think for two minutes and don't let Dumbledore decide that the sixteen-year-olds will be solving all the messes. Yay Order members who actually do something significant!