Minotaur BirdMan Rides Again

Question: How did Zwazo transition from the moral mortal Marcus James to the insane wrecker of everything? Also, what does he do with the humans in despair who find his realm?

Ah, Marcus James... he tried, the poor soul, but it just wasn't his destiny to be a reasonable and calm and noncrazy person, and Fate knew it long before he did. There was a time when he tried to be the conscience of Geoff's ragtag band of misfits; he refused to drink, tried to prevent unnecessary violence and even had a few Justice boons rattling around in his bag of tricks. But Marcus never really had much in the way of reason and patience in him - that was his twin, Mathias, and when Mathias died at his visitation he started to unravel. African myth has a concept called marasa, sacred twins, a single soul in two bodies; Marcus was the strong, active, passionate twin, while Mathias was the calm, intelligent, thoughtful one. They balanced each other when Mathias was alive, but without his other half, Marcus became unstable.

He managed to hold it together for a while, but the final straw that broke him was in the siege of Paris, when he beheaded a Scion of Teutates in a misguided attempt to save Goze from her, not realizing that she was administering a just punishment for Goze's many crimes. The Psychic Prison extended to him and trapped him in his own mind for the equivalent of several decades, and while Goze came out of the ordeal with a new realization of his sins and determination to make them right, Marcus went the other direction and came out irreparably mentally scarred. For a while he swapped between different multiple personalities, most of them violent and confused, and after Shango interfered to try to whip him back into shape, managed to pull it together to a sort of level of constant low-grade craziness.

Believe it or not, he's actually doing better these days than he was circa Legend 7 and 8. When he hit apotheosis, he was recombined with the spirit of Mathias, so Zwazo Fou Fou is in actuality once again both twins united. Mathias' influence has had a slight calming effect, and Zwazo is now more able to think before acting.

Unfortunately for everyone else, that basically just means that his insanity is capable of planning ways to get around them or manipulate events into benefiting himself, but at least he's not routinely crashing through other Scions' shrines or assaulting nymphs on Olympus anymore.

Edit: Sheesh, way to fail to answer the whole question, me. Marcus actually doesn't do anything with the lost and despairing mortals that enter his Sanctum; they simply travel alone and despondent through it for anywhere from days to years, probably without even ever seeing him (he isn't home much). The idea behind mortals having access to his sanctum is that they must be truly unable to cope with their lives anymore, or truly disconnected enough to become lost from their own world. When they do so, they wander through the desolate emptiness of his Sanctum until they either want to be part of the world again and fall back into it (usually to discover lives that are in total disarray due to their absence or to have to start from scratch) or die. Marcus himself generally ignores them.