Sitting at the vast desk, far too big for a mere human, Roboute Guilliman gazed at the dataslates before him. The Emperor's great dream was at an end it seemed. His crippled father was set upon the Golden Throne, the Crusade had ended years ago, becoming the heresy of his brother Horus which too had come to an end. With his accursed brothers driven back to literal oblivion, there was now the matter of Guilliman himself and his remaining brothers. Those that had remained loyal.
Only Dorn remained in any semblance of contact. Jaghatai still roamed the stars, putting out what fires sprung up in the wake of the Heresy. While Vulkan, Rus, Corax, and the Lion had all retreated to their home-planets to...Guilliman didn't like to use the word 'sulk' but he didn't know what other descriptor to use. None of them were unscathed by what had transpired, and all of them were finding their own ways to cope with it.
Guilliman for example was diving deep into administrative matters to ensure that the fragile Imperium didn't collapse in the wake of their father's crippling. He already had a matter of great importance to discuss with his brothers, an attempt to prevent the Heresy from ever happening again. However there was another matter on his mind at the moment, though of equal import.
Not every son of the traitors had turned traitor in turn. Many had remained loyal and continued fighting for the Emperor. Now though that left Guilliman with a conundrum, what to do with the traitorous children of his fallen brothers?
They had served loyally, and the thought of simply eliminating them rankled. There were some obvious solutions though, many of them could simply be adopted into the Ultramarines, but Guilliman didn't want to have them all under one single legion lest they form an isolated bloc within said legion. He may be able to convince Dorn to take on some of them as well, granted he was already planning on splitting the legions. Not that he'd told his brothers yet of his plan. That would come later, and would likely be a much more vexing conversation.
If he could convince them of the merits of each absorbing some of the remaining loyalist members of the traitor legions, he could spread them apart enough that any possible later unification and betrayal between them could be limited and contained if not outright prevented.
It was the most sensible option in Guilliman's mind. It would prevent the wasting of valuable and veteran Astartes, while also mitigating the risks to the Imperium.
Setting aside the dataslate for the time, he began to write his ideas down, carefully sorting each contingent of the loyalists into new formations to mirror those that he hoped to create with his Codex Astartes.
Death Eagles...Silver Skulls...Space Sharks...Blood Ravens.
There would be others, there had to be others. It would just be a matter of sorting them all into their various contingents, and then assigning each to a new primarch and lineage, ensuring that their fallen history would be sealed and forgotten by the Imperium henceforth. It was just another necessary lie, one of many that Guilliman had found himself telling ever since the Heresy had first begun.