Kairos Fateweaver is a Lord of Change.
Official Canon Edit
Being unable to see well into the future, Tzeentch had Kairos go to the Well of Eternity and forced him inside. Kairos emerged with two heads; one head speaks the truth, while the other lies.
TTS Canon Edit
Tzeentch uses Kairos to tell him if he's going to win his next Children's Card Game, if he's not feeling too lazy to ask.