Whitest-Eyed Demons Possible
Zachariah became very defensive upon hearing Castiel's extreme proposal to restore the humanity of an undefined number of demons, only to turn them into demons once again. The former employee of the month for too long to count was around personally when Lucifer corrupted Lilith and ended up caged by Michael as punishment.
"Castiel, surely you already know what happened to Lucifer because of what he did, right?" he scorned at the proposal put forth.
"We need the whitest-eyed demons possible, and many more of them," the tall man in a simple trench coat drove home his point and shocked his heavenly audience, "beginning with Crowley himself!"
"Well," suspired Anna after her inner contemplation, "I gotta second what Castiel wants done. Besides, it's not like we're corrupting innocent souls in the first place."
The former human female discerned that the suggested deal recognized the strengths and weaknesses of the whitest-eyed demons proposed. Without angel-killing weapons, these elite ones could still defeat regular angels and send them back to their heavenly origins. However, while lesser demons could proliferate their ranks, these ones could not. Before the recent angelic upgrades, a primordial entity of archangelic power was the minimum requirement for transforming a human soul into a white-eyed demon, let alone the whitest-eyed demon possible. Now, other high-ranking angels with sufficient augmented power could perform the same feat, including Holy Living Ones, Valiant Ones, and Electric Ones such as herself.
"Even then," Hannah chimed in, "you higher angels can bring into existence only so many of these whitest-eyed demons. Keep in mind that our enhanced Seraphim, while capable of smiting these hostiles with ease, number only in the hundreds. Furthermore, to add to Anna's suggestion for backup, you will need dozens of Seraphim."
"Points acknowledged," the tall man in a simple trench coat conceded.
The entire grand council extended the deliberation on the matter further, only to pass every recommendation made and assign Castiel himself, as well as the Holy Living One Phanuel, the Valiant One Raguel, the Electric One Tzadkiel, and the Fiery One Sahaquiel, to mobilize the necessary numbers of Seraphim, Strong Ones, Children of the Strong Ones, Cherubs of the first class, and Supernal Men to execute this deal with Hell.
Author's Note: The whitest-eyed demon type suggested above is intended to have all the strengths and other non-weaknesses of the white-eyed Lilith, the yellow-eyed Azazel, and the Knight of Hell Cain without the Mark. Also, as this fanfic is part of an AU follow-up to Season 11, no Princes of Hell exist in the overall follow-up, so Azazel is just a yellow-eyed demon.