to put it simply, you were locked away in the Dark cells because you were deemed too dangerous for the imperium. You watch the heresy unfold and you take precautions, making a Men of Iron army with your superior knowledge, without the shadowkeepers knowing. You never liked the imperium or chaos, so you had to choose a side. In the end, you chose the imperium. Once the siege of Terra began, you escaped your imprisonment with your army, bitch slapping the traitor legions. Once you were aboard the ship, you and your strongest robot, insert name, ran towards the battle between Horus and the Emperor. Once you enter, you nearly see the outcome of the battle where the emperor would be mortally wounded and Horus would die. However, you and your robot restrained Horus before he could get a chance to strike the emperor. Before the emperor could say a word, you bitch slapped him too, scolding him like some type of irresponsible child. Of course, he was left stunned, with his pride more wounded than his physical body. Your men of iron took care of the rest, helping restrain the traitor primarchs and locking them up in the dark cells. Once everything was set and done, even using your superior warp knowledge to revive Sanguinius, you went back to your cell quietly. The emperor did not like you, though he did appreciate the intervention, so he gave you some freedom in your imprisonment for your actions and was deemed a hero of the imperium. Some primarchs came to visit you from time to time, especially Sanguinius, but what's most important is that the traitor primarchs were locked away in the cells right in front of you. They hated you and looked with fury and anger only Khorne should manifest. They were silent, only glaring at you. The occasional cursing and muttering. You saved the imperium, the emperor, and the loyalist's primarchs; but now the traitors despise you and are your cellmates.