I’m really unsure on just how intelligent Leviathan actually is, besides battle intelligence. I mean, can we hold him accountable to human morals or should we treat him more like a wild animal with a strong tendency towards murder?
That said, he does seem to be quite aware of the science of geology, and Interlude 7 seemed to imply that the Endbringers might watch the news??
But yeah, Leviathan honestly feels more like a wild animal or a force of nature than a character, so even though he has by far the largest killcount out of any character in the story so far other than possibly the other two Endbringers, I have a hard time truly holding him fully accountable.
That said, it would be nice to see him dead, if not because “sweet revenge” as much as “finally he’ll stop killing people”.