HAAA! I love Harry clutching the sheet up (OH NOES, DOGGIE CANNOT SEE!!), with his knees bent up and and Snape with his lil' pinky bent! Nice details--Hedwig's perch, scattered socks, the lube and handcuffs. But it's the bright pink dildo and the dog's grinning white teeth around it that made me snort MY coffee.
Wonderful job, I love the implied scenario and the 'snapshot at the perfect time' feel to this!