If the Hime Festival is cyclic, perhaps Lavos (or a member of its race) actually revisits the planet on a regular basis, with the Black Prince as its avatar/core? It sounds vaguely as if the Mai Hime world is somehow important to Lavos -- perhaps for reproductive purposes? As in, the Hime chosen as the Black Prince's bride becomes the mother or host of a new Lavos fetus ...
Lavos, itself possessing a sort of symbiotic relationship with Mai's race, creates Hime by unlocking the potential of genetically strong mate candidates. The battle royale is initiated as a means of identifying the strongest of the strong, who then becomes the mother of the new Lavos; the Festival is a complicated mating ritual.
In which case, it's possible that the Mai Hime world is in fact the homeworld of the Lavos race / a reproductive rendezvous point that they return to and journey from? In the context of Chrono Trigger, the race of Mai's planet are an indirectly related (the relationship may be facilitated by Lavos influencing the humans of the Chrono Trigger world) genetic forerunner to the humans on "Earth", and are thus actually proto-humans (perhaps more genetically similar to Lavos than anything else).
Extrapolating this a bit further: Lavos is capable of autoevolution based on the genetic materials of the worlds it comes across, but perhaps continuous change causes it eventually to lose coherence. The non-asexual reproductive cycle could somehow work alongside the asexual spawning we know Lavos to be capable of to maintain both genetic variation and species identity? The "males" of Mai's race are simply stand-ins for Lavos to allow for the continual generation of females in order to facilitate the cycle. In truth Lavos and Mai's race are one and the same? (a race of 3 sexes: Males, Females, Black Prince / Manly Men
)
On the other hand, Mai with active Hime abilities could reasonably become a fiery invader from the heavens herself ... She can survive both space and reentry of the atmosphere without so much as a burn. >.>;;;;
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The Child that is manifested in higher-order matter with the awakening of the Hime might somehow be an expression of the Hime's personality and soul. With time, though, it's not inconceivable that the relationship between the Hime and the Child becomes equivalent to that between the Black Prince and Lavos. This means that the Hime's human body, originally the source of the Child's manifestation, evolves into a sort of avatar/human interface. The core of the being lies in the Child. It's never really mentioned in canon, but the killing of the Hime might cause the Child to become an Orphan? Orphans = female Lavos? Manifestation of a human avatar may be possible ...
Going by this, Kagutsuchi (actually millenniums-old version of canon Mai) might appear as some sort of draconic creature that Chrono and crew encounter, and then manifest a human "Mai" as an avatar? Or, in the alternate Chrono Cross timeline where the Saurians/Draconians never died, she's somehow turned into the Dragon God and fused with the elemental control system in Dinopolis? (she's later pulled back in time with the Time Crash?)
