Chiron shifted his gaze from Hope as he answered her question with the same tone that he always used. "Because killing him directly is too kind for him."
In other words, Chiron wanted Kace to feel all the heart breaking moments, feeling how devastated those people who lost their loved one, and so that he felt the same agony that he had created upon them.
Killing him was too kind, because Kace would just experience one pain and then he would be free, but by living, he would feel worried over his mate, witnessed the death of the creatures that he had killed, and watched a life that he thought was meaningless turned out to be so meaningful in the eyes of others.
Sometimes, being alive was worse than death.
That was the punishment Chiron wanted for Kace. If he could survive through all of this, he would find peace with himself and with his past.But if he couldn't, no one would be able to save him.
