He is a fairly simple youth from the fictional village of Arni. His journey takes a turbulent start when he is swept through a dimensional rift and ends up in "Another World," a parallel dimension that is strikingly similar, and yet quite different, from his. There he meets "Kid," a feisty thief who is equally mysterious. The appearance of Lynx, as the antagonist searching for the hero, thickens the plot, and so the journey to bring the worlds together begins.
When he was very young, Serge was attacked by a panther demo. His father Wazuki took him to the demi-human inhabited island of Marbule to seek the antidote. Never reaching Marbule because of a Maelstrom, Wazuki, Serge and their friend Miguel landed in Chronopolis, a military temporal research facility from the future, instead. There, Serge was exposed to the Frozen Flame, a mythical artifact, and healed. Wazuki, however, was corrupted as a result, and became the demi-human Lynx. When the storm subsided, the Prometheus Circuit (a.k.a. Robo) listed Serge as the "Arbiter," the only life-form to access the Frozen Flame directly, which hindered the Chronopolis' mainframe computer, FATE, to control the El Nido Archipelago it created. It downloaded its mind into Wazuki, transforming him into Lynx in order to oppose and eventually kill Serge. In Another World, Lynx drowned Serge in 1010 A.D. at the age of seven.
It is later discovered that Schala Zeal, the princess of the civilization that contacted the alien Lavos (Chrono Trigger), had caused the storm. She did this in order to save Serge, so that he can save her in return from melding with Lavos, and thus saving spacetime.
Home World, where Serge actually did not die at the hands of Lynx, was created thanks to "Kid," that is Schala, as a result of having traveled back in time after the events in Chrono Cross to rescue Serge from Lynx.
Serge is currently married to Kid, and she has embraced her identity as Schala.