Kallaya appears to be a mute child who has lived her life in the wild. This isn't true. This young girl is actually an ancient demon summoned by the Children of Shadow to build an army for an attack on the Twelve Kingdoms. She appears shy, calm, and numb to everything around her, but her powers go far beyond that. True, she may not be able to speak, but she can transport herself from one place to another in the blink of an eye. She displays great skill with trickery and magics and is shrouded with mystery and death.
Kallaya finds the lost and shivering Ali Callidrin in the forest south of the West Road, and leads the Callidrin to her summoner, a Shadowchild named Timothy. She's weary of when Ali makes her alliance with the Wildling Folk, and ever since Kallaya watches her every move. When Ali begins to notice she stops, feigning disinterest. She helps the Children of Shadow make a plot to destroy the group of Wilders, who were sent south from the mountains to find a stray group of White Sorcerers.
Not long after she creates her plot to destroy the Wilders, Kallaya begins to put it in action, watching as it throws confusion into the already small group as their members go missing. She discovers that Ali has made the connection that Kallaya's name is also the name of a demon, but she hasn't realized that Kallaya is that demon. She enjoys watching her enemies crumble, but decides it's enough and moves her plan along. The Children now spring their trap, waking the Wilders from their sleep, saying there are horsemen coming, then running them into a trap and shooting them down. But their plan goes astray when they realize there are actually are horsemen coming and two of the group escape and two are captured. Kallaya and the Children make their escape into the trees and appear to simply vanish.
After the time when Kallaya seems to disappear, she appears again, this time in the Marble City of Ohara. Once again she has a plot to put the war into the hands of the Children. She's meets Levolyn Silayen and two of her guard in one of the backstreets of the city. She appears to them as a slave, ragged and torn, to gain their sympathy, then hands the Lady of Dragons a quill and piece of parchment. She tricks Levolyn into writing on the parchment and it dissolves into a Sandsnake. Then she makes her escape, jumping down into the well and transporting herself to the top of the next rise, looking back to see if her scheme worked. It failed and she's seen, but only by the three she tried to murder. Kallaya then disappears again and it's unclear if she'll return.
Kallaya is a fiercely strong demon spirit, though she never shows it while playing others. She constantly puts on a fake personality, mostly shyness and dejection. Outwardly she appears weak and poor, unable to lift a weapon with the body of a five year old peasant girl. Inwardly, and heartfelt, she is strong, powerful and deceitful, even fooling the Children of Shadow who summoned her from the depths of the First Hell. She's constantly trying to overthrow people who could threaten the Children's secret rise to power. When Ali, Ines, and Dorian escape the death trap the Children set for them, Kallaya begins hunting them down, without the readers knowing. Kallaya is titled in fantasies and legends the Vengeful Death Demon of the First Hell, one of the twelve demons believed to reside in the crevices of the world.