Darios is a character from Fire Emblem Warriors. He is the prince of Gristonne and the son of King Oskar as well as the childhood friend of Lianna and Rowan. He is eventually possessed by Velezark, the Chaos Dragon.
Darios arrives in Aytolis at the beginning of the game, and spars Rowan while Lianna watches. After defeating Rowan, Lianna is about to spar with Darios herself when the Gates of the Other World suddenly open, causing monsters to flood the palace. The three work together to fight off the monsters, and meet up with Queen Yelena to make their escape. However, while running through a cave, Yelena is separated from the rest by large boulders, and gives the Shield of Flames to Rowan and Lianna before urging them to go on without her.
After that, Darios continues serving as a mentor and ally for the twins as they find heroes of other worlds to power up the Shield of Flames with the heroic orb essences from the chosen heroes called Gleamstones.
When the Gristonne army, led by Validar, attacks the Ylisse and Aytolis armies at Aytolis’ dragon temple, Darios becomes disillusioned by his father's betrayal and begin to cast away his loyalty from his home kingdom.
During the the heroes' attack on a Gristonne fortress, Darios is trapped inside the castle and unable to escape from the enemies’ barrier, thus ended up being possessed by the dragon Velezark before the heroes arrived and rescue Darios. Because of Darios' hidden lust for power and obsession to become stronger, Darios ended up becoming Velezark's perfect host, who corrupts his will. After all Gleamstones were gathered into the Shield of Flame, Velezark, using Darios' body, initiates its plan. It reveals itself as Oskar's co-conspirator and steals the Shield of Flames for their own evil purposes, and so the twins pursue him.
When they catch up to him, they find that Oskar and the Velezark-possessed Darios also have Yelena hostage. Oskar and Darios prepare to sacrifice Yelena to revive Velezark's full power, though Darios makes the proposal that if the twins surrender their weapons, he will spare her. When they do so, he turns to kill her anyways, but is stopped by Takumi, who predicted this outcome. The twins retrieve their weapons, and Rowan forces Darios back as Lianna rescues Yelena from the magic circle she was being held captive in.
With Yelena rescued, the twins attempt to get Darios back from Velezark's possession when Oskar approaches him. Darios reassures his father that the situation is under control before suddenly stabbing him in the stomach, saying that all he needed was royal blood. With Oskar as the sacrifice in Yelena's place, Oskar's body is absorbed by the magic circle to fuel Velezark's full power into Darios' body. During the battle against his fellow heroes, Darios manage to fight back Velezark from the inside for the heroes to defeat him.
After the twins defeat him, Darios fully regains control over himself and pleads for them to kill him before Velezark manifest itself from his body. They refuse to, and believing there must another way to save Darios, but was too late. Velezark begins to separate from Darios' body, using the Guston prince's life force to materialize its body. Although Darios is freed from the dragon's possession, it is short-lived as Darios pushes the twins away from one of the dragon's attacks and is impaled by a sword. Using the last of his strength to return the Shield of Flames, the floor under him gives way and he crashes to the depths below as the twins scream his name.