"Remembering and being human are two different things." Grandpa cut him off. "Those memories are still there, but they're only ornaments hanging from a demon's soul. The roots have already rotted. No matter how much you water it, it'll never grow into a human tree."
Kus opened his mouth, but no words came out.
Grandpa handed the detector back to him, but Kus did not take it.
"Kus." Grandpa called to him, his voice suddenly soft, just like when he tucked him in late at night many years ago. "Do it."
Kus raised his head and looked into those dark red eyes.
"Only after seeing you did I suddenly remember the past. I don't even know how long I'd forgotten those memories."
"If I stay here like this, what will I become? Keep killing people, eating people, and turn into a real monster!" Grandpa took a step forward. "I can still remember you now. I can still speak like a human. But in a few more years, even that will be gone."
Kus gripped his knife tightly, his hand trembling.
"What did I teach you when you were little?" Grandpa asked.
Kus closed his eyes. "Kill what deserves to be killed."
"Then what am I now?"
Kus opened his eyes.
He looked at that gray-black face, those dark red eyes, and the bone spurs protruding from behind his back. "Something that deserves to be killed."
His voice seemed to squeeze out of his throat.
Grandpa smiled. On that savage face, the smile was still the same as it had been in his memories.
"But..."
As he hesitated, Grandpa unknowingly drew closer step by step. Suddenly, red mist rose in his eyes, his nails turned into dog-like claws, and black energy seeped from his body as he charged at Kus.
At