Oh, that was lovely! I can just see the wizarding world reacting like this to aphasia, treating Harry like an idiot child, and Harry withdrawing from everyone in frustration and despair. It's so sweet how Severus comes to understand his fractured speech - and I love how Severus' favoured teaching method (shout at Harry until he explodes) actually bears fruit in this instance!
Just beautiful - and with a hot, sweet ending! I adored it! :D