Well, on some level that started already in Chapter 4, with the Hammer of Justice introducing the idea of Lightners being reborn in Dark Works as Darkners under very specific circumstances.

But the Flowers really put that point front and center. They are living things that receive some sort of Wish-Fulfillment in the Dark World, much like how our Lightner characters receive cool outfits and powers… but the main Wish being fulfilled for them is having a higher form of consciousness and a more anthropomorphic form, like how Darkners come to life in the Dark World. Flowery’s portrait is Black-and-White, much like the Lightner characters, because he is a kind of Lightner as far as the metaphysical mechanics of Light and Dark function… except he also has colorful Darkner-like Golden eyes.

And so much of the conflict of this Chapter is based on their unique liminality. They’re Lightner enough that being reduced back to their Light World ‘inanimate’ form feels much more like a death to them then it feels to a regular Darkner (who can find contentment as inanimate objects, as they are ‘alive’ from the Dreams the Lightners associate with them)… but also Lightner enough that they can’t actually survive for long in the Dark World, their physical bodies still have their regular physical needs, but unlike Susie, they also can’t exactly pull out of the Dark World, grab a snack for nourishment and then pull back in.

And then the Secret Boss is another kind of Liminal being, a more traditional Darkner (in the sense of a truly inanimate object come to life) that’s also being brought to life due to being possessed by a Lightner ghost. Another sort of unique being who is not quite as Ontologically Doomed as the Flowers, but struggles with figuring out what her identity is in her own way. She feels more at home with other Liminal Beings like the Flowers, despite being technically a different kind of being.

All of this feels like build up to exploring the nature of Ralsei, the so-called ‘impossibility’, who already has some of their own ‘Liminal’ elements - they look much more ‘like a Monster’ than any other non-Gerson Darkner, they can appear and survive in every Dark World, and from a meta-narrative perspective, their role as a Darkner Playable Party Member seems to clash with the game’s meta-commentary making Darkners to be like a whole species defined as Video Game NPCs on some level.

They don’t quite seem to match any of the ‘Rules’ of the Liminal Beings we know of so far. Resurrected Lightners like Gerson are specifically mentioned to only appear in very specific Dark Worlds, so this is like the opposite of Ralsei’s situation, and even with their white fur, their portrait seems considerably less monochromatic to me than Flowery’s. But I think this is still a thematic build-up being done to explore different kinds of liminality between Light and Dark and how they affect the relevant characters, before we get into the particular kind of liminality that Ralsei represents.