Darius

Darius is coward and very shy dragon.
Darius is very small compared to his brothers, Jax and Zeke.

His brother, Zeke was very violent towards Darius when they were little. Jax tried sometimes to help Darius, but he couldn't always look after him. 

Darius couldn't protect himself at all, so he went to one vendor, who sells enchanted crystals. Darius said to the vendor that he doesn't want to be weak anymore, and that he wanted to protect himself.
Vendor gave him one crystal, but didn't say anything about what the crystal really does. Darius decided to trust the vendor and he bought the crystal.

Little did Darius know, that crystal changes him to a demon dragon. It's very opposite of Darius's personality.
Darius gets 10x larger when he's in demon form.
Crystal changes Darius when he's scared. 

When Darius grew up, he moved away from his family to life on his own. He didn't want to hurt anyone with his crystal form.