#kurogen

P.S This ramble somewhat contains spoilers for Dr. Stone. I suggest to scroll down to avoid any/read the manga to understand the whole context. I'll try to make it as spoiler-free as possible.

P.S 2: This is a sorta continuation to this post. It contains lore details I'll be referencing here, so be sure to check it out. Thank you :33.

For this au in particular, I've been lately considering: "What if Senku Ishigami had a superpowered evil side?". Then, while scrolling for ideas, I saw a comic about Senku using Why-Man to transform into a black-haired version of himself and whooping ass, and suddenly everything just clicked in my head:

Crazed expression? Obviously villianous red-black color palette? Hero's other less-than-pleasant side? It all came together.

And thus the Kuro Senku, aka just Kuro, of this AU was born. The not-so heroic side of the noble demon Senku Ishigami — aka Senku Astaroth. Strap in, this is gonna a long post.

Origin

Senku is the Head of the Astaroth (Ishigami is the last name he adopted on 'overworld', aka our Earth.), who in his possession has the power of petrification. Crudely speaking, it's the same thing as canon Medusa: the power is a green light that petrifies everything within given reach during given time. Senku himself is immune to it unless under certian conditions (like repel skill).

Kuro is not a separate entity. Rather, he's a product of a phenomenon called Personification — when a power takes 'physical form', through possesion or otherwise (Kuro is former). He's a little bit of everything: Kuro, in a sense, is not just the essence of Senku's powers in a living form, but also an embodiment of the former's darker desires for control and greed for knowledge — hence the chaotic personality. Speaking of which...

Personality

It is important to note that Kuro is not Why-Man, but he shares many character traits with it.

Kuro's core characteristics are the same as Senku's, being an alter ego of him and all: he is straightforward, confident, and ambitious, while simultaneously being his host's opposite.

Unlike mellow and charismatic Senku, Kuro is aggressive and condescending. He's prideful, rejecting negotiations while preferring establishing his dominance mainly through violence. He, at least from 'normal' human moral standpoint, is evil. From his standpoint? It's complicated.

Kuro is driven solely by curiosity. The power he embodies is as capable of healing as it is of killing. Problem is, Kuro is incredibly chaotic and selfish. He's only acting in his interest: to study various species and 'experiment' on them. And while Kuro is capable of compromising, he only cares if any side is offering any significant benefits. Otherwise to him everyone is a potential test subject he can put through fate worse than death as much as he pleases.

He's also a horny little pest since sexual development is a part of his interest to study but cough coUGH COUGH SHUSH

Relationships with Gen

Like with many other things, Kuro first and foremost finds Gen interesting, more than anything else. Kuro finds it difficult to understand why Senku protects and cherishes Gen so much, since he himself never was attached or fell in love. He's an extension of Senku, so he can't and probably never will.

Kuro is obsessed with Gen, or rather with that he can't hurt Gen. The golden necklace? Senku gave it to Gen not just a sign of their love, but as a way to protect Gen from Kuro. The Devil's eye contained within it was a vessel that suppressed the chance of Senku's petrification ability going out of hand, but now that it's in Gen's possession, Kuro is much less restrained — Senku sacrificed his control just so Gen would stay safe.

"Why are you wearing that thing?" "Why does Senku like you so much?" "If I were to torture you, would he feel rage?"

Kuro expresses his 'attraction', or rather obsession, through crude language: he's not afraid to tell Gen what he wants to do to him — torment him, put him through fate worse than death to test him limits. Kuro is one of few with who Gen feels genuinely uncomfortable around. He only loves Senku, but Kuro also demands attention. "I'm a part of him. You can't just ignore me, right?"