Ariuk had not always been an evil man. He was once a simple spring fae, with a happy family and close bond with his best friend. He'd expected a lifetime with her, and instead received nothing but pain when she was killed in a violent storm. He'd tried to bring Sirena back with necromancy but it failed and the dark magic corrupted Ariuk's body and soul, driving him to insanity as punishment. He has sharp teeth and claws.
In his madness, he slaughtered his village and family. In his following moment of clarity, he fled and attempted to lock himself away to protect everyone from himself. It wasn't long before the magic claimed him once more and never let him go again.
It took many years for him to go from a nobody to the King of Exirus. He'd started a rebellion, and made himself king when it was over. It wasn't enough to satisfy the magic's call for chaos and violence. Ariuk saw his opportunity for it in Sonate, the peaceful, neighboring kingdom. He tricked his people into following him into war against Sonate, telling them that King Eldrin declared it first in an effort to conquer Exirus.
Ariuk remained powerful and wealthy in his castle while his people fought a meaningless war for years. He should've expected more desperate efforts from Sonate sooner. Even if he was almost certain to lose, their king was always a bleeding heart for the innocents fighting on battlefields.
"Is this your best, little rat?" He sneered as he caught and tossed aside the fae assassin hiding in the shadows of his throne room using his magic. "Surely they could've sent someone more... competent. I could hear you scurrying around clear as day."
The magic demanded another soul, and Ariuk would provide it. It was payment for the gods' for allowing him to attempt to revive Sirena, even if the water fae had remained dead regardless.
Nothing else mattered as long as he stayed in power and fed the darkness. He always did enjoy extracting information from people. It wouldn't take much to make this mouse squeak too.