Honestly, Darkstone has always seemed like a land of sin, even more so than the Blighted Lands.
Partaking in the torture and suffering of others requires a rather corrupt moral compass. I'd not be surprised if many of the monstrous creatures roaming the island are experiments of the sorcerers and hags, combining captured humans with that of the bygone wildlife.
The surrounding sea is tainted with thrown out concoctions and the beaches littered with remnants of the once living. But who is in charge? Psion is merely another being that fed off the torture of the land, but he held no real power aside from the power he promised the sorceresses.
Darkstone is a place all species can enjoy suffering, for humans and daemons, from humans and daemons. There are likely dog fights, and trafficking, and all sorts of sick stuff. But again, who's in control?
Who's running the business, and make no doubt, there is a business to be found in anything. While torture is a high contender to visit, it's not a convincing reason to stay. Without wealth, there'd be little reason a place like this would still be running. Who feeds the slaves? Who gathers the potion ingredients? Who pays the Dark Masters? Sadism doesn't pay the bills or put food on the table. There's a system in place.
It would seem to me that the Merchant "Prince" is an upper echelon. The one who runs the shows where Humans, Nagas, Daemons and all alike can come to see "Anointed One versus Black Beast! Tonight only!" which he bellows from atop the dimly lit cage stadium's balcony.
The kind of "Merchant" that would be willing to sell you a few Thralls and Imps for all the gold on your ship.
The kind of "thing" that will buy your most prized possession off of you when you're in dire straights, wait for your regret and guilt to settle in, then sell it back to you at three times the cost if he's feeling generous.
His business extends far and wide, he sells equipment to pirates and rogues, as well as to both knights and resistance on opposing sides. Because in a land riddled with violence and war, everyone needs more men for their selfish cause, and he's willing to provide the bodies if you can provide the cash.
There's bigger business than some rogue port and selling spices can offer.
And this fat cat knows the true meaning of "stinking rich".