Warhammer: The 11th Primarch - The Black Emperor
Nareth was chosen by the Sefirot "Kingdom of Disorder," altering his fate from the gestation pod and giving the Chaos Gods a little shock.
During the Great Crusade, he expanded the empire's borders.
In the Horus Heresy, he slew the traitorous Primarchs.
After the Emperor ascended the Golden Throne, as the only remaining Primarch, he became the one to put out fires across the galaxy.
In the War of the Beast, he struck down the Beast.
In the Eternal War, he made traitors tremble in fear.
All praise his loyalty—but was that the whole truth?
"Actually, I was just in it for the benefits.
"What? You didn’t notice? With the potion ingredients, I could nurture Beyonders.
"Belisarius Cawl was my ‘enlightener’..."
"I am the shadow of order, finding every exploitable loophole in the rules."
He is the Black Emperor, the one who dictates the laws.
He forges a new empire and carves out a future for humanity, drowning in darkness and despair!
Daoist_Jinzu · Anime & Comics
This story is a RWBY fanfic with someone with the knowledge of RWBY reincarnated into the body of Ruby Rose's brother. Although it has slight grammar and spelling mistakes, and the main character is too OP and flirtatious, overall it is quite well written.