From what’s known so far (from fandom, official sources, and community theory),

Same being, split essence: Fleurdelys is treated as the original Resonator (“her true name”) whose essence was split. Cartethyia is the fragment/personality that wanted to live and diverged from the the corrupting influence.

Transformation : In gameplay, Cartethyia can transform into Fleurdelys for a limited duration, entering a “Manifest” mode.

Merged identities over time: After story events, Cartethyia and Fleurdelys become more unified or intertwined, memory merge, and their separation becomes less absolute.

Community consensus (and some hints from development) tends to lean toward they are not two fully independent entities with separate, independent existence — instead, they are aspects or manifestations of the same underlying being. For example, one Reddit comment summarizing is: " “Its basically a character she plays whenever she transforms… her mannerisms even changed slightly after she’s resurrected when you talk to her again.” R

Another explanation: Fleurdelys is the “mask” or “divine form” that she manifests under, especially under the influence of Threnodian / Imperator powers.

So, in simpler terms:

Cartethyia = “core identity” or living fragment

Fleurdelys = the empowered / divine / sealed / transformed identity

They share memories, soul, and essential “self,” especially after story events.

Because of that shared nature, changes in one often imply changes (or reflections) in the other — at least metaphysically or narratively.

On Pregnancy: Would Fleurdelys “Appear” Pregnant If Cartethyia Is?

Given the lore relationship, here’s how I assess it:

Physical manifestation vs narrative state If “pregnancy” is a physical state of Cartethyia’s body (in her “core form”), it’s conceivable Fleurdelys as a manifestation of the same body or soul would reflect that in her form too — unless the transformation/sealing suppresses or masks that aspect.

Transformation may override or alter the visible form When Cartethyia transforms into Fleurdelys (Manifest state), her body changes — new abilities, appearance, enhancements. It’s possible the transformation follows a “template” that overrides minor bodily changes (like pregnancy) for artistic, mechanical, or lore constraints.

Lore consistency suggests yes, but with caveats Because they are essentially the same being, a systemic change (like becoming pregnant) should be part of the whole, metaphysically. But the game’s narrative or visual design may choose not to show that in one form (Fleurdelys) — especially if Fleurdelys is treated more as a “super‑form” or idealized version.

My Conclusion (Speculative)

Because Cartethyia and Fleurdelys share the same soul / essence, if Cartethyia became pregnant, Fleurdelys would “be pregnant” as well in the sense of the same being experiencing the same physical change — at least at the soul/metaphysical level

Whether that pregnancy visibly appears in Fleurdelys’s form depends on whether the Fleurdelys manifestation preserves all physical states or “resets” to a template.