Pens scrape softly in the library, faded green ink that spirals out and melds together into little scabs until Vexen is forced to blow his research dry. The pages ruffle squeakily, testing their bindings; the books do not remember how to flutter properly, their noise an octave off and an age away. His temples ache, tugging gloved fingers up to scrub at their needy flesh.
Silver strands strangle the table, Dusks rippling into tangibility. Vexen snivels, turns his nose up at the creature; this is not the one he called for, or if it is then it is not minding its tasks. No hot water bottle graces its leathery palms. Not anything he was looking for, except perhaps a test subject.
"If you won't be useful, then be gone."
So when the Nobody's jaws unzip, and the mouth beneath gapes wide, and a third mouth whispers back "Who am I?" Vexen is left ill prepared and with only moments before it sinks back into the darkness.
The next time he sees a flicker of skin, Number IV takes hold of the Dusk. It is bound by both shackle and magic, though in a universe where doors refuse to stay shut for long and the locked is pried open by overeager schoolboys, his precautions are ill advised at best. Vexen peels back pale tissue one strip at a time, searching for the vessel that beats steadily inside the Dusk's human layer.
Something that makes it have eyes and a mouth beneath the shell.
Flesh dissolves quickly, into piles of molten shoe and castaway rubber. He isolates the tissue, separates it rapidly from oxygen or fluoride or any other wandering particles that could possibly throw off a Dusk's composure. Plays hell with the temperature—and in the end, Vexen concludes that he can never truly isolate his subjects from the darkness.
The last three dissolve before he can finish his vivisection.
A Dusk can go headless and neckless, though which half is alive is a source of debate in the Organization. Dusks have never needed limbs, only most of their body, but never their heart, and irrevocably their soul. But in a world where the heart is the seat of emotion and a cage for the body, and the body carries a mind and will of its own, the worth of a soul is questionable.
"Perhaps that's the line." It creeps into his hair with the morning dusk, bleeding into Vexen's skull like putty through a sewage grill. The idea continues to itch until he's brought crawling back to the library, scraping Demyx off his chair and casting the nocturne out the door.
The Dusks are bodies animated by their own will. They have a shape, dictated by the lingering sentiments of their former self, but these are shallow impressions of the Dusk's once-ruling heart. With the throne of the heart empty, they bend to the Organization's will, congregating under ranks and banners that spit out words like Berserker or Dragoon.
But the thirteen overseers of the Organization have a different master to answer to. Vexen is Even with half of the man stripped away, and Nothing to fill the void. They are animated by the soul, and continue to echo more strongly the sense of being them.
The answers aren't ready to face him in neat equations. The best equations are never neat, and that's hell for Even, but Vexen can manage. He didn't feel anything tremendous with the loss of his heart. His hair felt a half inch too short, and the bangs a little more rough to the touch, but the odd emptiness in his chest was easily put aside. Saix can't testify to that level of control. The diviner pines for his other self. An immature heart and active body, or a soul better fed and maintained than the throne it was supposed to service.
In a word, they were born heartless.