"Did you know?"
Her birthday starts with accusations-
"Know what?!"
"About Mr. Weasley's bite?!"
-it gets worse from there.
Vague excuses aren't accepted by Hermione, who can't fathom such a thing being forgettable. So she's quickly abandoned.
Letters never arrive from home, and her housemates's are unware of the day's significance.
She turns 16, alone.
Deciding to retire early, finds a golden bracelet on her pillow. A single line in a recognizable hand reads;
Per Tradition.
And she chokes back a sob.
10 hours later Sprout is shaking her awake.
"...?"
"...it's your parents."