His sole purpose

"I got it from you, mother."

The girl possessed with a fragment of his mother's soul froze as soon as the words fell out of his mouth. She overcame the shock rather quickly as the next second Hex buckled and fell to his knees, pressed by an invisible weight. 

"Mother? Is that so?" 

She had crossed the distance between them without Hex noticing, and stared in his black eyes as she whispered, although it sounded more like a hiss. 

"Yes," Hex spat, finding it very difficult to maintain his rationality and will to speak. Uttering even that one word tore his lips and hurt his jaws. The air pressure even put tears in his windpipe. But he didn't wish to lose to her like the last time they encountered. He was stronger. He should be stronger. But to his dismay, against a Sin Stage Being it didn't matter whether you were a Knight or a Refined Knight.