The Watcher (dream)
Harry knew it wasn't fair, but he was cheesed off at Ron.
The one night he finally managed to fall asleep and not have some Voldemort-induced nightmare, and what happens? He's awoken anyway because of Ron's dream.
In his sleep-deprivation, Harry wondered what would induce a nightmare in Ron? In his grumpiness, Harry wondered what really gave him the right to writhe and grip at the sheets?
What would cause Ron to moan his name and slowly rotate his hips?
Realization hit Harry like a Bludger.
Well, maybe it wasn't so bad to be woken up by one more dream.