What Do You Mean Guilliman Founded a Second Empire?

The Emperor arrived on Macragge, expecting to find an ordinary Primarch son, just as he had when he found Lion and Russ.

The Emperor: "What do you mean Guilliman founded a Second Imperium and made himself Emperor? Magnus is his Hand? Angron is his Warmaster? Perturabo is Minister of Science? Lorgar Aurelian is Minister of Propaganda? Konrad Curze is Grand Inquisitor? Mortarion is Minister of the Interior? Fulgrim is his captain of the Custodes?"

Lion: "Ambitious Guilliman is bound to rebel. We will have to fight the Second Imperium."

Listening to the intelligence reports from his assassins, Malcador asked, "What do you mean Guilliman used Old One technology to build a Webway city beneath Macragge and is now laying Webway routes across the whole galaxy?"

Horus could rack his brains all he wanted, but he still couldn't understand how an unremarkable guy like Guilliman had won the undying loyalty of so many brothers.

Guilliman wore Gothic golden power armor, held a greatsword powered by a flaming dimensional engine, and sported a fluttering crimson cloak.

Looking at the eighty thousand Custodians and the Primarch brothers behind him, all of whom should have rebelled, Guilliman awkwardly said to the Emperor, "Father, if I say I'm actually loyal, will you believe me?"