Overview
This world has an odd mix of of magic and art deco era-style technology, with the occasional glimpse of something either totally magical or a bit of technology that's openly superfuturistic. It's also completely overrun with demons, and the borders between the human world and the realm of demons are flimsy at best. Whether seeking power for its own sake, to rule the world, or looking for revenge against someone or something (perhaps even the whole world), it seems like every few years, someone on one side of the divide is trying to rip open a portal between the two worlds, to conquer the one on the other side. Of course this lets out all manner of demonic beasties. Whether or not they're under the control of the one who released them, they represent a continuing threat to humanity.
For now, focus upon the plight of Vie de Marli, once known as Dumary Island, originally colonized by refugees from the Mediterranean who were persecuted for their continuing worship of pagan gods. These refugees, as well as runaway slaves, created the culture there on the island. Eventually the people of Dumary Island began to worship beings from the Demon World, believing them to be gods from other planes of existence. At the head of these services -- rituals much like the sealing and exorcisms of demons -- were "guardians", powerful priests who borrowed power from these otherworldly entities for the purpose of protecting their people against malicious "gods" -- other demons.
The legend of the Demon King Sparda even touches this remote and tiny island off the coast of the Americas of this world -- using the Arcana, the holy relics of the Vie de Marli clan, he aided the guardians of Dumary Island in sealing away a horrible evil known as Argosax the Chaos. He was, however, trapped in the Demon World. Temporarily. Fortunately he escaped.
Fast-foward to the present day, where a man named Arius, the CEO of the Uroboros, a very large public corporation, builds a skyscraper called "Skyscraper Sanctum". His stated aim was to collect some sort of ores found only on the island. But in truth, he sought the Arcana as a means to release Argosax the Chaos and absorb his power. Eventually however, with the demon hunter Dante and Lucia, one of the few femaining members of the Vie de Marli clan -- those "with the blood of devils" -- Arius was defeated and Argosax was sealed again.
However, with the World Tree and its vines providing portals to different worlds -- and to the forbidden places within this world as well -- how long will it be before something else nasty is released? And will it confine itself to this world... or will it threaten all of the World Tree with its evil? After everything the people of this world have been through, no one is eager to find out, and would really rather the World Tree keep is business -- and its villains -- to itself.
Vie de Marli
Descendants of the first "guardians", who borrowed the powers of their "gods" to protect their followers, and to defeat and banish evil gods from the human world. The island is called "Vie de Marli" now, possibly as a tribute to the clan who first bore that name. It deserves to be noted that the membership of the Protectorate is not, was not, and never will be, restricted to females only (as the BradyGames guide for "Devil May Cry 2" erroneously notes). Lucia and Matier are simply the only members currently, and they both happen to be female.