If they didn't…
They were not human.
As Arthur thought those words, a smile began blossoming on Oscar's face. His eyes were still fearful, but his body reacted vastly differently to what the former conveyed. Soon, his eyes unfocused.
His facial skin peeled, forming scars that eventually weaved into a pattern. Two lines emerged from below and above Oscar's ears, curving downwards before colliding near his nose. Blood emerged from the torn skin.
Oscar stood still, maintaining a faint smile on his face.
Arthur, sensing the growing intensity of Oscar's power, retreated a few meters. Skofnung remained by his side on standby, and with focused eyes, he concentrated on the changes on Oscar's body.
His entire constitution was shedding.
Arthur watched calmly, yet he felt a sense of anxiety surge from within. The changes in Oscar's body and mind weren't natural. It was as if a being contradictory to human nature was possessing Oscar's body.