There was once a weak little sparrow. She has yet to learn to fly, so she fell out of the nest. Little did she know it would keep her alive. In a small stream she drifted on by as the other creatures burned alive, a fire engulfed the forest she once called home. It nipped the edges of the stream burning her wings, as time went by the fire died leaving the entire forest in ash. A lone witch searched the forest with tears in her eyes for any signs of life.
Only to find a lone little bird, barely clinging to life, desperate to survive. So the little witch took the little sparrow home, trying to save its life. Her wings were badly burned, and she would never be able to fly. The witch did what she could and kept the bird alive, but as time went by the sparrow grew sad. Knowing everything was gone, and she was alone as she looked at the burned forest.
Then the little witch had an idea, to try and turn the sparrow human, so they wouldn't feel so alone anymore. She didn't see the agony that would cause the sparrow, and never expected the burn scars would stay. So the little sparrow was turned human, well mostly. The witch has to teach her how to be human, which took many years. Eventually they lived comfortably, enjoying each other's company, but good things never last.
Someone from the nearby village saw the little witch and her small hut. They were suspicious of her, hating anything different from them. They looked disgusted by the other one, the sparrow didn't look like them. Not only that, but they hated the witch and chained the sparrow, forcing her to watch as they burned the witch. They studied the odd girl, wanting to know what she was, why she was different. The torture seemed to never stop, till she finally broke, harnessing the witches power and the life of the ancient forest that was burned. The ancient forest where she was born was burned by the villagers and the magic went into the little sparrow, hoping she would survive.
She went into a fury, slaughtering the village, leaving nothing left of the ones who tortured her, burned her only family alive and destroyed her home. She when she finally calmed, she was on the mountain overlooking the dead forest and decimated village, realizing she was truly alone.
A cute little short story I did for a character backstory