When we cut open his head, a gray fluid came out and he stopped moving. Our conclusion is that humans need something called a "brain". But we changed him into a form where he'll never get angry. What a good thing we demons did!
Then you realizehow Zelenin's song affects the Earth in the Law ending. In SMT, demons, angels included, are basically thought elementals. Each demon effectively signifies a particular aggregate of thoughts. Zelenin's effect on the demons basically means the song dissolves any kind of idea other than glorifying the Great Will. Mastema and the Wise Men are trying to mindwipe the planet!
Any path that isn't Neutral. Law? The Earth's population is converted into a mass of worshippers with absolutely no humanity left. Chaos? Earth dissolves into a barbaric anarchy unable to think of anything but getting ever stronger and stronger, thanks to Mem Aleph suffusing the whole planet and finally in a position to prevent infection by anything that could succor weakness and decay. Like sanity and calm. In a very real sense, both factions are hostile to the mind as we know it—because neither side regards there being more than one kind of good thought to have. While in either ending, the last shot you see is your Demonica telling you your mission is complete...yet you'll probably be thinking otherwise.
One of the parasites communicates with Zelenin...and gloats about how her crewmates on the Elve not only looked down upon her for being a woman in male-dominated company, but had sexually depraved thoughts about her.
The various sectors represent humanity's sins in ways that can make you feel...funny, to put it nicely. That the endbosses of each sector calls out humanity for being bastards doesn't help.
Sector Bootes, the Frivolous Nation. A realm full of nauseating colors, corpses tied to the walls and horrible, smiling doors. It's Mitra's way of convicting humans for desiring pointless things.
Sector Carina, the Squandered Nation. Laugh at the whole "shopping mall in a dimensional rift in Antarctica" thing if you must; it's a Player Punching commentary on humanity's desire to excessively spend and consume. The Apsaras at the entrance puts it best: "Please enjoy our products until the Earth runs out of resources!" Also notice that among the wares are all manner of modern weaponry—even though, going by the ABCD cycle, those embodying Carina should be well past needing weaponry for much of anything. Basically, this is Chaos insisting that no matter what, life will always be addicted to fighting (the "crime" is trying to pretend otherwise). Then we have Horkos, who plans to eat anything and everything, even everything on Earth, and calls out mankind for even being more material-hungry than he is. And if you pick the "Law" response—that humans can learn to restrain their impulse—he castigates the very idea of self-restraint as foolish and inherently impossible. He thinks the only answer is to actively and consistently destroy and abolish things that aren't actively needed. Further Fridge Horror results when you realize he isn't expecting self-restraint after he and the Schwarzwelt have finished the current round of culling the unnecessary, either. Whether he knows it or not, he's inviting a world where everyone tears at everyone else for what they want/need without any chance to rest—just the way Asura wants it, actually.
Sector Delphinus, the Rotten Nation. It's, quite simply, a massive waste dump, with familiar things peeking out of the literal walls of trash—cars, machines, trash bags, fish skeletons, etc. The area is simply so desolate and disgusting it's hard not to remember humanity has probably done worse. The music's sombre tone only reinforces this.
Sector Grus. Psychological Torment Zone, created by a mistress of Mind Rape. Invisible walls, fading walls, several dimensions, Demonic Spiders galore, and a random mishmash of the first four sectors, which most likely evoke the worst parts of the Schwartzwelt Expedition. Mother Maya's lair is worse- it's an impossible mess of worlds struggling in a vortex of illusions, generating the madness that is Sector Grus.
The Game Over screen. With nothing left to stop it, the Schwarzwelt absorbs the entire Earth, leaving just a sphere of darkness. And given who incited it to begin with, it's probably much the same result as the Chaos ending...
Dent's fate if you go Law and finish all of his missions. He's content everyone else is happy. So he no longer needs to feign being equal to you. Cue a moment of horror as he starts groveling and addressing you as "master", making it clear he's just as hopelessly mad as everyone else.