He hadn't told anyone about the Grim, not even Ron and Hermione, because he knew Ron would panic and Hermione would scoff. The fact remained, however, that it had now appeared twice, and both appearances had been followed by near-fatal accidents; the first time, he had nearly been run over by the Knight Bus; the second, fallen fifty feet from his broomstick. Was he going to spend the rest of his life looking over his shoulder for the beast?
And then there were the Dementors. Harry felt sick and humiliated every time he thought of them. Everyone said the Dementors were horrible, but no one else collapsed every time they went near one ... no one else heard echoes in their head of their dying parents.
Because Harry knew who that screaming voice belonged to now. He had heard her words, heard them over and over again during the night hours in the hospital wing while he lay awake, staring at the strips of moonlight on the ceiling. ...
"Because Harry knew who that screaming voice belonged to now." looks like an incomplete sentence, but ended with a full stop instead. I suspect if it's a special use of the word 'because'? Any thoughts?