A witness of inhumanity might think of a thing or two in regard to the reason why such acts were committed by the aggressor or punisher. But in the end, there was only the undeniable, irrefutable truth which was a person's nature.
It could be due to one's psychopathic tendencies; one's sociapathic behavior; one's unfulfilled revenge, or one's will to protect those that configured his or her existence such as loved ones.
However, such a saying was that a cycle of one's own actions also exists. It's either the source of malice or the receiver of it. As such, in this ancient-looking, illusory ship, Azel and Olivia witnessed their Young Master's emanating malice, which he bestowed upon those who indifferently showed it to those undeserved.
Zero had no joy in killing someone. For him, these heathens were only in the way of his goal. Unfortunately, they deserved an agonizing death as leaving these heathens alive would far endanger other innocent lives.
