8. Alpharius and Omegon, Primarchs of the Alpha Legion
Spoiler alert! If you haven't read the book Legion you may want to look away.
Still with me? Okay, it was revealed that the Alpha Legion has two Primarchs who are exact duplicates of each other. They were distrusted by their brother Primarchs because of their secretive ways. Unlike the other Primarchs who were physically much larger and more powerful than their legionaries, the twins are only slightly bigger than an average marine. They had to fight differently than their brothers and as such used deception and misdirection on a scale that was seen as repulsive to the other Primarchs. Ask any Alpha legionnaire who is Alpharius and they will answer, "I am Alpharius."
I guess I put them so far up the list because they are so unique among the Primarchs and their characterization in the book Legion ,to me, make them very interesting.
7. Mortarion, Primarch of the Death Guard
See what I did there Death Guard fans?
Anyway, like so many of the traitor Primarchs, fate wasn't so kind to Mortarion who as a baby landed on the planet of Barbarous which was surrounded in a poisonous fog. Everyone except the rulers who lived high above the poison fog, everyone else had to endure short painful lives. Mortarion thought this was wrong and led the populace against their despotic rulers, one of whom had sheltered the young Mortarion. Mortarion felt guilt and the thought of killing the person who had rescued him even if that act could not forgive the horrors his adoptive father reeked on the human populace.
Mortarion was almost successful but relented in killing his adoptive father. When he returned to the humans they told him about a stranger who had arrived while Mortarion was waging his war. This stranger was interested in him, and wanted Mortarion to come with him to a place called Terra to be one of twenty princes.
Mortarion was confused, why would this man be interested in him? Mortarion didn't want to leave the people he had sworn to protect but the stranger seemed adamant.
Finally, the stranger offered him a compromise:
Defeat the tyrant who was Mortarion's adoptive father and the stranger would leave.
Fail and Mortarion would have to come with the stranger.
Mortarion confronts his erstwhile father but cannot overcome him. As he is at death's door the stranger appears and with one sure strike he kills the overlord.
Mortarion must go with the stranger.
Mortarion is not happy.
The stranger turns out to be the Emperor of mankind and Mortarion learns that he is one of the Emperor's twenty sons called the Primarchs.
Mortarion is presented as being the reaper, striking from the shadows.
His fall to Chaos might seem very obvious given the enmity that Mortarion felt towards the Emperor for taking him away from his home world and killing his adoptive father when he had failed. Still Mortarion is a deeply nuanced character that I found interesting.
6. Magnus the Red, Primarch of the Thousand Son's
Cyclopean Magnus as he is known was wise, but his wisdom brought him arrogance. I find it fascinating the philosophical questions that are brought forth with Magnus and his role in the Horus Heresy. Magnus is the only psyker among the Primarchs and at first this gives him special status with the Emperor who is the most powerful psyker to ever exist. Magnus delves too deep for the Emperor's liking and is rebuked officially at the Council of Nikea by the Emperor along with his brother Primarchs.
Does Magnus give up? Of course not and as he is looking where he shouldn't he detects the daemons of Chaos trying to ensnare Horus. He tries to help Horus, but is defeated. Then he warns the Emperor that Horus has been turned. He is correct, Horus had been turned, but the Emperor refused to believe him because Magnus had violated the edict of Nikea.
Magnus decides to show the Emperor using his psychic might and in so doing unleashes the daemons of the warp on Terra. Oops!
Magnus's hubris leads to his downfall as the Emperor orders Leman Russ and the Space Wolves to destroy him.
But the fact remains; Magnus was right.
Is doing something wrong for the right reason okay?
Does the fact that a decision is wrong mean that everything that comes from it wrong also?
These questions fascinate me, and Magnus bring them out so I rank him high on my list.
Looks like I've gotten a bit long winded. So join me for part 3 of my ranking the Primarchs!