Oh, this is so cute -- I love the idea of Severus as a writer! I totally had to laugh when he said, distractedly of course, that he finally figured out how they escape the tunnels. I know what those middle of the night fits of creativity are like, and in fact keep a notebook by my bed, too. I also had to smile at Severus being a blanket hog (comes from all those years of sleeping alone, I suppose) but could feel the warmth Harry felt when he dragged them back over the top of him. You've just conveyed so much in so few words.