The things they lost in the war.
In an unexpected twist, Hermione was the least enthusiastic out of all of them to go back to take their NEWTS. Harry and Ron both insisted they needed passing scores to be Aurors (though Kingsley would have had them even if they got straight T's), but when they asked Hermione how her studying was coming, she looked at them oddly.
"What's the point?" she asked.
Harry and Ron stared at her as if she'd grown an extra head. Ron cleared his throat and scratched his head. "Er—say again?"
Her eyes were on them, but she wasn't seeing their faces. She was seeing a tent set up on ice-crusted ground, a dragon flying away from Diagon Alley, Bellatrix Lestrange's face staring back at her from a mirror, Bellatrix's laughing face with her wand raised as Hermione screamed and screamed…
"After all we did," she started, her lips moving slowly, strangely. "It just seems silly to get worked up over something as trivial as grades."
Later, she dug out her old copy of The Standard Book of Spells, Grade 1. She remembered how a little bushy-haired girl had devoured the book eagerly, memorizing everything. She remembered how she had stayed up late the night before tests, going over and over the material because grades were everything. Grades were the only thing that told children how successful and knowledgeable they were. Logically, those with good grades would go on to achieve great things, and those without would not.
But grades didn't matter when you were staring death in the face, or when a madwoman was sending fiery spikes of pain through your body that made you wish for death… In the end, the people who died at the Battle of Hogwarts were not the bad students; the survivors were not the ones who had gotten all O's on their OWLS. Death was unbiased.
She missed those days when her greatest worry was whether or not she'd scored the extra credit point on her Charms exam. Life was much simpler that way.
Hermione put her forehead against the cover of the book, but no tears came: only a bone-deep, infinite weariness.
She studied because she felt she had to, but she got no pleasure from it as she had once done. It was Harry and Ron who set up their study sessions. She merely drifted along with them.
Hermione Granger got all O's on her NEWTS.