Steel

Steel is the companion and heart of Aradia. He once was one of the Guardians, fought Aradia in the first war and lost to her. She managed to infiltrate Steel and corrupt him from the inside. Since then, they share a symbiosis where Aradia protects him and feeds him dreams. In return, Steel can connect Aradia to dreams of Guardians, called a Garden.

Past
Steel was the Guardian of freedom, he was one of the most free spirited Guardian. As such, he was capable of entering Nightmare World without the need of being a nightmare. But his arrogance and confidence pushed him too far inside enemy territory. When the Assembly sent Hunters after him, he tried to escape but got cornered by Aradia. Exhausted by the fights he managed to reach the portal to Dream World, Aradia trying to stop him, jumped and dashed toward him. In the same motion she grabbed his heart and melted inside it, they both passed out.

When he immured, Steel felt bitterness, angriness and then fury, he was different... Instead of appreciating freedom like he used to, for the first time, he felt the need to be free. He soon realized that he was part of Aradia now and could feel what she felt. Corrupted to the core, he lost the sense of being a Guardian, or even a dream, to become the first Nightmarecatcher. The only thing he wants now is freedom, he will get it, one way or another.