Perilune

When a celestial body forms, its soul manifests as a dragon, and seeks out the nearest inhabited planet to hunt upon. The moon dragon's power is cataclysmic on Earth, as she draws her strength from the gravitational force which creates the ocean's tides.

Thousands of years ago, a violent king cursed a fragment of the moon; anyone who held it had the dragon's perfect obedience. The king used her as a weapon, destroying countless lives in his conquests.

After the king's death, his heir decided such a weapon was inhumane for war, but too valuable to relinquish; The dragon was commanded to remain in her prison beneath the kingdom forever.

Enraged, she began to kill any human who entered her cell. Rather than command her to stop, the royal family found her to be an efficient executioner, and an effective threat to dissenters.

When Lyra is sent into the dragon's cell, fear conflicts with empathy, as both have suffered at the same hands.