Meryl sacrificing herself to give Harry, and Lily, a chance.
Aurora's death at the end of Summer Knight can definitely bring a tear to the eye:
'Wait,' she said, her voice weak and somehow very young. She didn't look like a mad faerie sorceress now. She looked like a frightened girl. 'Wait. You don't understand. I just wanted it to stop. Wanted the hurting to stop.'
I smoothed a bloodied lock of hair from her eyes and felt very tired as I said, 'The only people who never hurt are dead.'
The light died out of her eyes, her breath slowing. She whispered, barely audible, 'I don't understand.'
I answered, 'I don't either.'
A tear slid from her eye and mixed with the blood.