The Leviathan is associated with anger and cruelty.
The Leviathan was born of the anger and cruelty of Selnoir and Alethia’s fight within the great ocean. A massive being of great power, its great tentacled form cannot truly be understood by mortal minds and all those who see it directly are driven mad. While it is said to live deep under the ocean, its reach is as long as it needs and it has been known to reach out from the abyss in every land to cause cruel harm to anything living. The Leviathan does not choose to kill those it preys upon, instead it seeks to cause as much anger and pain as possible to anything it can, and is considered the father of torture.
The Leviathan is a being of great evil, and its desire for pain is akin to a great hunger. It actively feasts off of anger and pain, and seeks only to consume more and more. Death interests it not at all, as the emotions it feeds upon die with it, and it will keep its followers, their prey, and any it can alive and suffering eternally where possible.
Cults of Leviathan are mad indeed, for they always face the pain and malice of the great demon during their worship. Through the pain and anger they gain, great power can be found for those who can endure it, but it is not intentionally given. The Leviathan cares not at all for those who worship it, and simply does what it can to spread anger and cruelty everywhere it can.