Kai and Nya’s father Ray fought as the Master of Fire alongside Wu, Garmadon and the Elemental Masters during both the Serpentine Wars and the battle against the Hands of Time. Ray is the master blacksmith who, along with his wife Maya, forged the Time Blades used to defeat Krux and Acronix. With peace restored, Ray eventually chose to blacksmith full-time and raise a family, passing his elemental power of Fire down to Kai.