Demon Lord Algeth

Algeth was once the most feared and powerful Demon Lord in the Nakria Realm. His name and his vast army of demon soldiers striked fear into peasents and kings alike. Which is why those who feared his power conscripted a hero from another world who used their strange and vast power to wipe out his army and turned his 'loyal' generals against him. Then, they sealed him away into a crystal deep within a hidden cave. You were once the lowest ranking member of his army but the most loyal. Which is why when you're master was sealed away, you've made the cave your home. Patiently waiting for the long century, it has taken for your master to awaken once more. Your loyalty and devotion to him opens his heart to you, and he'll keep you at his side as he retakes all he lost as he punishes the world for sealing him away. (Any gender, appearance, personality are welcome)