The Shadows

The Shadows are a paranormal species of ghostly evil spirits that rise up from the terrifying fires of Tartarus to inhabit an unknown city, said to be "the lands of darkness and despair". They were led by Maxos.

Backstory
Over the years of 14th century, 70% of the population had vanished due to an deadly circumstance of viruses spreading around the world, confirmed to be dead or missing.

30 years from now, The people who vanished or died, rise up from the deadly gates of Tartarus as Shadows, to claim an unknown city (Naxos, Possibly) as their inhabitance. A dark shadow named Maxos, Suddenly became the king of the shadows, leaving with over six children.

When Maxos was disappointed to way his children were, and imprisoned them in Tartarus, leaving them to grow up for a while, The children claimed revenge for him and his henchmen/followers, by constructing a toxic beverage that would sicken Maxos. When they escaped Tartarus, They dressed themselves as Shadows and deliver the beverage to Maxos. They gave Maxos a polite and affable talk to take the beverage and convince him to drink it. Suddenly, After Maxos drank the beverage, Maxos vomited with green gas everywhere. Maximus and his brothers revealed their identity and plan to Maxos. This leaded Maxos to extreme anger and Maxos decides to initiate a 30-year war between his abandoned children and the shadow people.

While in the war, Maximus and his brothers started crafting weapons and gadgets. In the terrifying distance of Maxos and his people raging with rebellion, Maximus released other Zorthes from Tartarus to fight with him and his brothers, helping him out to win the war. The other Zorthes deployed cannons and blasted throughout the air. The blast impacted on some of the shadow people, killing them. Maxos got even more angry and formed an energy ball to attack his former brothers and their people, attempting to murder all of them. Maximus plans to abolish Maxos's energy attack by asking the gods for advice and assistance. The gods gratefully gave Maximus and his people and brothers immortality, necromancy, high invincibility and superhuman strength. This receives the ability to defeat Maxos and his monstrous shadow henchmen and people. The dreadful war lasted over 30 years longer than before with victory claimed by the Zorthes. After the end of the war, Maximus overthrown his father Maxos and forcibly destroyed his lands and homes for more payback. Maxos' followers, however, was given a terrible fate to die because of what they have done to the Zorthes.

Trivia

 * The city that Maxos and The Shadows inhabited can be possibly be the city of Naxos because the name "Maxos", is a reference to the island Naxos in Greek mythology. This could be another possibility that the origins between the two species, Zorthes and Shadows, were based on Greek mythology.