"Please, do it," she groaned.
"Why?" he asked, tears were starting to roll slowly from his eyes.
"You heard the healers, I won't last much longer anyway." Her voice was barely above a whisper.
"But that will be time for us to be together," he persisted.
She lifted her hand to his cheek.
"We won't really be together. I will be lost in my world of pain, and you will be fighting to keep me here."
A heavy sob tore from his lips.
"Please," she whispered.
He nodded silently, and placed a soft kiss to her lips. He raised his wand to her temple. He looked her in the eyes as he said the words.
"Avada Kedavra."
The spark instantly left her, and his tears started to fall freely.
"I'm so sorry," he gasped through the tears.
So, a random thought came to me today, is there ever a time where Avada Kedavra could be used for good? That's where this came from.