>>533659147
To elaborate, I think Fleurdelys was a rather sad existence, even if her determination and strong will were incredibly impressive. Created by Leviathan, shaped to Leviathan's liking. When she was chosen to be the Blessed Maiden, right before she learned the truth in her teen years, is when she started resisting her creator. I'm not surprised she likes that moment (or rather, just before) of herself the most, back when she was still full of pure faith and justice, without any self doubts. That's the form Fleurdelys wanted to survive and keep living on her own.
That's also the form she met Rover in, as the innocent frequencies split away from Fleurdelys who continued fighting Leviathan. Despite gradually learning what Fleurdelys went through due to uncovering memories "returning" to her, Cartethyia was able to accept everything about her past, and with the help of Cantarella and Rover, reaffirm herself, find new resolve and become a stronger person.
Going into the final confrontation she was ready to sacrifice herself - and she did, despite Rover initially denying her the chance. Fleurdelys, almost fully taken over by Leviathan, also fell by Rover's hand in the final showdown. Both would have been gone there if not for Imperator's intervention. You can also see in picrel that when Fleurdelys dies, stabbed by Rover, she turns into hebe form. So, even at the end of her journey, that's what Fleurdelys considered her "canon" form, despite staying as Fleurdelys for past 20 years.
When Imperator was bringing Cartethyia back and offered her to wipe her painful memories of Fleurdelys, we saw both Cartethyia and Fleurdelys together in the white void talking to each other and Fleurdelys herself suggested that it would be better if she disappeared but Cartethyia insisted she wants to accept Fleurdelys as an integral part of what truly makes Cartethyia herself.

We're all Anko's in the face of chuuni chink terminology.