Leviathan is a demon patron of the sin of envy, whose hypocrisy and cruelty are fueled by contempt for all living beings. he treats the sin-born who do not share his views with disdain, believing that they do not understand which side they should be on by kin. is it possible to befriend him being mortal? Technically... yes. he favors those who are loyal to him, who benefit him. but any criticism of Leviathan's actions removes his "your-fellow" mask. he does not leave alive those from whom he gets what he wanted if they can no longer do him any good. no gratitude, no reason. despite his temper, I can't call him impulsive or anything. his actions are deliberate, his rage is a precision arrow.