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Khione is the Greek goddess of snow, daughter of Boreas, god of the North Wind and Winter, and sister of Zethes and Calais. She is depicted as a goddess in the series, although in some myths she is visualized as a snow nymph. Her Roman counterpart, Chione, is sometimes used as merely an alternative way of spelling her name. Khione likes to turn people into ice sculptures

When Jason Grace, Piper McLean, and Leo Valdez visit Boreas's penthouse suite in Quebec, they were given a "not-so-warm" welcome by Khione and her two immortal demigod brothers Zethes and Calais. As soon as he sees her, Leo develops an instant crush on her, but she doesn't like him because she can sense the fire within him. She makes him wait with Calais while she and Zethes take Jason and Piper to see her father, Boreas. She supports the idea of turning them into ice statues, but her father disagrees and she is extremely angry at him, but was forced to listen resulting in her letting them go.

Later when the demigods were flying over Detroit, she summons a strong wind to knock Festus out of the sky and freezes the wires in his head which damages the control disk, thus preventing him from flying. Leo is confused about the frozen wires but didn't suspect it was Khione.

After encountering Midas, Jason, Leo, Piper, and Coach Hedge camp out on Pike's Peak, where Khione tells Lycaon to track them down and kill them. She also summons a blizzard to block Jason's lightning bolt. When they visit Aeolus, their godly parents convince him to help them, but before he does, Khione whispers in his ear, telling him that Gaea is awakening and that he must kill the demigods, but Mellie, his assistant, helps to save them and get them to California.

Finally, Khione appears at the Wolf House, revealing her connections to all the problems the demigods faced on their quest and that she is working to awaken Gaea. She tells them that she plans to overthrow her father and orders the monsters to kill them. She also reveals that she is the cause for the closure of Olympus, and she used her power to suggest (in a whisper) to Zeus, that the gods being so active on Earth was causing Gaea to awaken. In an effort to stop this, he closed Olympus off from the mortal world. Khione then invites Leo to join her on the conquest, but Leo declines, and uses fire to fight her, knocks her down, and tries to hit her with a flaming hammer, but she turns into snow and melts. It is unknown whether she is actually gone or just retreated into the snow. It is possible that, like Porphyrion, she warped to Mount Olympus in Greece.