Whee, I loved this! So much! Every time I go 'I don't want to see another H/D for the next year', something like this pops up and all resolve goes out of the window :).
The setup with the curse scars and the magical bond inflicted by Harry's Sectumsempra was inspired, and I loved Draco being lectured by Snape's portrait about his behaviour throughout, and most of all about honesty with himself :).
And the gradually deepening acquaintance between Draco and Harry was just plain lovely. I was particularly fond of the first encounter when Harry throws Draco out, because it does full justice to the fact that they don't like each other at the start (wonderfully canon). And the 'let's play Quidditch until we tire' was so in character, and I loved Minerva coming to wake them up and the way she sees right through both.
Some fun touches, too - Draco remaking Harry's bed to his own preferences had me in stitches. Well, that, and him catching Harry in the shower and being unable to walk away :).
Loved this was self-seduction, and by the looks of it, Potter had seduced himself quite thoroughly.
I loved Harry's straightforwardness throughout, although it felt most endearing in bed, and the way it does all sorts of things to Draco ;). I loved the bit of bickering and the tiny touch of dominance in Harry (and his insistence on being called 'Harry').
And '...so you're saying we fried the lights' was hysterical!