Schala is a non-playable character in the Chrono franchise, and the prominent link between Chrono Trigger and Chrono Cross (she also appears in the Satellaview Radical Dreamers). She is the daughter of Queen Zeal in 12,000 B.C., living in the Kingdom of Zeal. She is perceived as one of the most powerful people in the kingdom. Because of this, the Enlightened Ones gave her a magical pendant that controls the Mammon Machine (a machine built to harness Lavos' energy) and certain sealed doors and chests. She is very protective of her younger brother, Janus, and as such he has a strong emotional link with her. A mistranslated line of NPC dialogue in the English localization of the game refers to them as step-siblings, but they are actually blood-related.
The Kingdom of Zeal
When Schala was young, it became known that the gentle princess of Zeal was meant for great things. She became friends with everyone, including the Earthbound Ones (humans not possessing magical abilities, whom are looked down upon by the Enlightened Ones; magic users that live on the floating continent). The three Gurus saw this in her, and gave her the aforementioned pendant.
When Crono and the party arrive and are subsequently captured by the mysterious prophet that had recently joined Queen Zeal's court, Schala frees them and requests that they free Melchior.; one of the three gurus, and whom had been banished by the mentally deteriorating queen. Unfortunately, the prophet discovers them and forces them to leave the era through the gate, which he then forces Schala to seal.
After managing to return (by finding the Epoch), the party free Melchior and meet with Schala at Algetty; the home of the Earthbound Ones. Here, Schala explains that she refused to activate the Mammon Machine. However, Queen Zeal's right-hand man Dalton arrives soon after and captures her in order to escort her to the Ocean Palace, where the Mammon Machine is kept.
At the Ocean Palace, Schala is forced to activate the Mammon Machine. The activation causes Lavos to temporarily awaken. After Crono is killed by Lavos, Schala teleports everyone else away from the incident. Schala is not seen again for the rest of the game, and her final fate isn't revealed until the sequel, Chrono Cross.
The Time Devourer
It is revealed that Schala was transported to an area known as the Darkness Beyond Time, along with the remains of the Mammon Machine, and Lavos. Lavos took advantage of this, and absorbed Schala to create the Time Devourer (allowing Lavos to literally consume time). This caused many things to happen within Schala. She still contained some of her human feeling and emotion, but it became mixed with Lavos's hatred for the world. With her human side, she was able to assist Serge from time to time.
Before Lavos completely takes over the human side of her, she manages to clone herself and sends the child (known as Kid) back to 1004 A.D., where Lucca adopts her. Because of this, Serge's party is able to utilize the Time Egg and Chrono Cross to defeat the Time Devourer and in essence, fix time. They also managed to separate Schala from Lavos's evil.
In Radical Dreamers, Schala is shown to be filled with guilt for her role in these events. The Frozen Flame (a small, yet sentient portion of Lavos) apparently reverses her age and sends her back in time to grow up as Kid.
The Dream Devourer
In the DS version of Chrono Trigger, it is possible to attain a new ending with a new final boss. The player must fight the Dream Devourer, a fusion of Lavos and Schala. This ending attempts to better link the storylines of Chrono Trigger and Crono Cross by providing context to how Schala becomes the Time Devourer.