Zilar was once a normal man of some weird exotic race. He's clearly not any longer and has lived centries passed his expected life span. Zilar is a mere shell of what he use to be and his old self is nearly forgotten to even him. Zilar now walks the many planes he has access to wishing to simply die and yet will never be allowed to do so.
Anyone with the ability to wield or sense arcane power may sense an immense amount of power inside of him. They would also depending on how attuned they are to the arcane arts might be able to tell the energy that Zil' has is tainted and appears dark in nature.
Zilar hovers around a "Chaotic Neutral" state. Despite being extremely reserved it wouldn't take a mind reader to tell this man struggles with his past and perhaps even his present. Something is always off with Zil, he's usually lost in his own thoughts though every now and then struggles to keep his anger in check. There's clearly something dark that is festering inside him and he's constantly at war with whatever it is.