If he hadn't grown up with kind people, then if Ian didn't have enough rationality and self-control, he was surely capable of doing something more crazy.
But a crazy person who is just pure crazy would just be a criminal, and Luciel wasn't interested in such a person at all.
In fact, if he met one, he would surely kill him or her because those kinds of people were those who feared nothing as long as they could cause more chaos and enjoy themselves.
He's only a bit more interested in people like Ian who are crazy but still in control of themselves, because as long as they're in control of themselves, they're crazy but certainly powerful.
Such people weren't afraid of many things, so unlike others who have more fears, they'll likely survive longer and probably stay saner than others in the world that they were in.
As long as they have a proper mind, they won't break easily and won't go crazy after years of seeing the world in such chaos.
