Chrono Cross (Lost Storyline of)
Signs point to another overarching storyline that involved Serge binding with the Time Devourer itself. In this scenario, Serge, if he did not defeat the Time Devourer with the Chrono Cross, would ultimately bind with it and cause the Devourer to mature, granting him the power to consume space-time.
Chrono Cross Ultimania supports this scenario, claiming that the Arbiter of the Frozen Flame must mediate between his fellow lifeforms and Lavos, or else he will inevitably bind with the creature and spell destruction for other humans. Ultimania also postulates that Schala was an Arbiter of the Frozen Flame while it existed in Zeal, and that is how she came to bind with Lavos. Apparently, the Time Devourer needed enough power before it could reach maturity, and Serge would have been the final piece in the puzzle. Quotes in the game also seem to hint at this possibility; three come to mind specifically. A demi-human in Marbule states that "anyone who touches that Flame will become a different being." Lynx, at Viper Manor, warns Serge that "there shall be a deep enmity between you and the world" once destruction occurs. Lastly, Belthasar notes that the Arbiter will gain "extraodinary powers...by binding with the new seed of destruction, the Devourer of Time." However, this storyline is not directly stated or implied in Chrono Cross, and neither has series creator Masato Kato confirmed it himself. For the time being, it remains speculation made by the Ultimania authors. Considering that in the same book, they contradict other canon (such as stating the Prometheus Circuit is not Robo, when Masato Kato noted that the circuit is Robo), its veracity is arguable.
[Book] It all began aeons ago, when man's ancestors picked up a shard of a strange red rock... Its power, which was beyond human comprehension, cultivated dreams... In turn, love and hate were born... Only time will see how it all ends.
almost definitely refers to the Frozen Flame. When the Ocean Palace Incident occurred, Schala would have escaped the first time around. The second time, she would have fallen into the distortion to merge with Lavos after his defeat. The Frozen Flame would then be without an Arbiter for some time, probably coming into possession of Guardia (or playing a role in its founding), as Radical Dreamers states that a "northern kingdom" kept the Flame for some time. After this, the Flame would be lost in the sea until 2300 A.D., when Belthasar would locate it and construct Chronopolis. It is unknown whether Belthasar would be an Arbiter as a result. At any rate, Serge would become an Arbiter in Keystone T-2, and would somehow serve as the final needed piece for the Time Devourer's evolution. Somehow, he would inevitably meet that fate unless he took action with the Chrono Cross. It is unknown if the Frozen Flame would still be active after the Time Devourer parent was destroyed.
From: Theory (Plot and Other)