1. The initial few corrupted marines are discovered and executed for corruption and disloyalty to the Imperium.
2.The great crusade continues on, however, several cracks begin to appear. The Night Lords, suffering from a breakdown in command, lose coherency. Gaining a small territory to claim for the legion centered around their home, they are effectively banished to protecting that sector. The Night Lords are reformed into a stable legion and Conrad Curze reverts to his original state of mind, sometimes leaving his territories when the visions reveal danger to the Imperium.
3. Lorgar, crushed at the loss of religion, begins to unwind with no sense of purpose. However, with the discovery of chaos exposed and how close he was to being used, he takes on new mission in the form of a legion completely devoted to routing out any who worship the ruinous powers and other heresies and executing them. The Inquisition is born. The Silver Blade of Laer is destroyed in this time by Lorgar. Fabius Bile is executed for extreme heresies at this time.
4. Already wary of the Emperor and seeing him as another tyrant, Mortarion is brought to task. Along with Perturabo, they are brought to the Emperor to be put back into line. Revealing a finished Human Webway Project, Mortarion is shown the Emperor's dream and his legion becomes an Imperial Arbites legion, roving the empire and ensuring that no system falls into tyranny. Perturabo is queried on his skills of construction, and is given the chance to create and build the Imperium in a manor suiting the Emperor. His legion is divided, with most following him into construction while his best and brightest are instead sent to serve to advise and educate the Imperial military.
5. Fulgrim's constant striving for success finally reaches its pinnacle with the solidifying of the Imperium. Fulgrim is given powers to effect efficient services in the Imperium and improving overall quality. The Administratum is reformed with him at its head while his legion act as enforcers and dignitaries.

6a. Angron and his legion are made a first reaction force and is made on permanent crusade, to eventually be wiped out in battle.
6b. Angron and his legion, starved for war at the end of the Great Crusade, march on the Emperor. The Emperor uses his powers to obliterate Angron, and the rest of the legion is put to death.
6c. Angron is brought to task by the Emperor. He is subdued and the Butcher's Nails removed. The remaining legion also has the procedure performed on them. They are now reliable and are sent out to join forces with the Space Wolves to form the backbone of the Astartes military forces.
6d.Angron is brought to task by the Emperor. He is subdued and the Butcher's Nails removed. The remaining legion is isolated and all new recruits do not receive the butcher's nails. They are sent out to join forces with the Space Wolves to form the backbone of the Astartes military forces. Those with the nails still in place are used as shock troops.

7a. Lion returns home and the Dark Angels are made hole again. Luther remains as second in command but eventually passes like those who also are not full space marines. Lion settles down to maintain a sector of the Imperium while keeping an eye for the emergence of new chaos forces.
7b. Lion returns home to discover that Luther has rejected the Imperium. Caliban is subsequently destroyed and Luther and all his marines are killed for being traitors. The Lion regrets the loss of his dearest friend but keeps watch in his sector for emerging chaos threats.

8a. Seeing the threat of chaos, the Emperor creates a force designed to combat the creatures of the warp. Using psychic powers, this force would repel the demons and keep them from emerging into the materium. This force would also be in charge of containment and ensuring that all granted with psychic powers are located, monitored, and trained for use in the Imperium. Magnus and his legion become the primary unit of this force, creating the Librarium, which also serves as the educational center and monitoring center for all space marine librariums.
8b. Magnus is discovered and chastised for sorcery. His legion is closely monitored and trained for use as Astropaths. They also are extensively trained to use the Human Webway and become an exploratory force for future human expansions.

9. Leman Russ is assigned as a leader of the the Astartes military against threats. Those who become Wulfen are used as shock troops.
10. Rogal Dorn and his legion are tasked with the creation of defenses and forward observation with the final settlement of the Imperium in the Great Crusade. Travelling from system to system, they build defenses to protect the Imperium while also setting up long range outposts designed to detect anything coming towards the Imperium. It would be these outposts that eventually detect the Tyranid invasion fleets.
11. Sanguinius and the Blood Angels become benevolent guardians of the Imperium. Those however, who feel the Red Thirst too strongly, are sent to fight with the Astartes Military under Leman Russ.
12. Ferrus Manus and the Iron Hands are sent to Mars. With their appreciation for humanity, the Iron Hands work with the techpriests to improve overall human life.
13. Vulkan and the Salamanders return to the Imperium at large, with the vast majority centered on Mars. Thought of as the greatest artisans in the Imperium, they work with Mars to usher in a new era of inventions and creativity under the Emperor's encouragement.
14. Corvus and the Raven Guard serve as elite troops under the Astartes Military, with Corvus serving alongside Russ as a leading tactician. Special units are assigned to the Imperial Army.
15. Roboute and the Ultramarines settle down in the expanded Ultima sector and proceed to govern it as they had before. The legion as a whole splits down into multiple divisions and dedicates itself to specific sections of the sector.
16. Horus remains one of the best tacticians in the Imperium, and remains the Warmaster of the Astartes Military.
17. Alpharius and the Alpha Legion disappear. They become secret police under the direct order of the Emperor, used to keep an eye on all threats to the Imperium.