With Sirius dead, Harry expected a summer filled with dark times, marinating on how he was to blame. What he did not expect was for the Dursleys to thrust a baby into his arms and declare it his. One night of recklessness was enough, but he refused to leave the baby with the Dursleys. Could he do this at 16 on top of school and extra Defense? (Mentor/Fatherly Snape, eventually.)