Kid is Schala's daughter-clone sent into the modern world. Kid was born in 1004 A.D., when Schala, bound to the Time Devourer, feared her mind would become increasingly consumed by hatred and created a clone of herself. She gave the baby her Pendant and sent her to the modern world; there, she was found by Lucca and subsequently adopted. Lucca soon established an orphanage and continued her scientific research, attempting to perfect the construction of Time Eggs. She gave a Time Egg prototype to Kid, and also provided her with an Astral Amulet, a magical pendant inside a purple pouch bearing the crest of Zeal. In 1015 A.D., Lynx and Harle sacked the orphanage and burned it to the ground. Kid managed to survive by escaping; she was scarred by the event and swore to get revenge on Lynx. Soon after she presumably was contacted by Belthasar and given the task to travel back in time (to the year 1010AD) to save a young Serge from being drowned by his FATE-corrupted father Wazuki.
Having done this, the Timeline split, resulting in parallel universes, one where Serge lives and the Day of Lavos eventually comes to pass (as Serge and Lavos are connected by the Frozen Flame), and the other where he is dead and Chronopolis is still constructed. When Serge travels between dimensions Kid soon finds him and they chase after the Frozen Flame (the events in Chrono Cross) leading to the creation of the Chrono Cross, a cross-dimensional element that was able to free Schala from the Time Devourer.