One of the twenty Primarchs created by the Emperor of Mankind for the Great Crusade, Perturabo and his brothers were scattered to the stars by the forces of Chaos. Landing on Olympia, Perturabo found by the guards of Dammekos, the Tyrant of Olympia, while crawling in the mountains. Recognizing he was no ordinary child, Dammekos took Perturabo in and raised as his own son. While Dammekos gave the boy warmth and affection, Perturabo never returned it. When the Emperor came to Olympia, Perturabo submitted to him and overthrew Dammekos. The fallen Tyrant would try to mount a resistance, but it would fail. Perturabo was given command of the IV Legion of the Adeputs Astartes, the Iron Warriors.During the Great Crusade, the Iron Warriors became masters of siege warfare, developing a rivalry with Rogal Dorn, Primarch of the Imperial Fists, with a similar mastery of sieges. The Iron Warriors were eventually relegated to single squads being expected to keep control of planets with millions of inhabitants. Perturabo resented this, and when Olympia rebelled, the Iron Warriors launched a savage reprisal. Soon called to Isstvan V to deal with the beginning of the Horus Heresy, the Iron Warriors defected to the Chaos Space Marines, and later reveled in destroying the ramparts of the Imperial Palace. After the Horus Heresy, the Iron Warriors defeated the Imperial Fists in the Iron Cage incident, and Perturabo ascended to Daemon Prince, ruling over the Daemon World of Medrengard in the Eye of Terror.
Badass Bookworm: Perturabo was a brilliant engineer and mathematician, which is where he got typecast for siege warfare. He wrote the Castellum Arcanum, the go-to guide for siege warfare among the Traitor Legions.
Combat Pragmatist: He preferred the use of combat robots as his personal bodyguards rather than fallible mortals and was more than happy to destroy an Iron Hands cruiser on first contact rather than waste lives boarding it. This brings him into conflict with Fulgrim.
Drop the Hammer: He was given Forgebreaker, the Thunder Hammer of Ferrus Manus, by Horus to seal the alliance between them. He was using Thunder Hammers before that.
A Father to His Men: Only in the literal sense, as the Horus Heresy indicates that even before declaring for Horus he was killing Iron Warriors who had fallen from favor.
Hates Everyone Equally: In the end. Despite being a largely unpopular primarch, he enjoyed spending time with Magnus as they both shared an interest in researching the great innovators of Terra's past.
Hidden Depths: Was in fact a cultured artist; the fact no one knew that pissed him off more.
My God, What Have I Done?: His reaction after suppressing the Olympian revolt, which is largely what encouraged him to join with Horus, as he praised Perturabo for his thoroughness. Staying with the Emperor left Perturabo facing penance he felt he deserved, joining with Horus gave him the forgiveness he desperately craved.
The Nicknamer: Gave the Eye of Terror its name, before that it was called Cygnus X-1.
Not So Stoic: Despite the Iron Warriors reputation for stoicism, Perturabo had quite a temper on him. In The Crimson Fist novella, it's implied that Berossus got placed in a Dreadnought because he had to tell Perturabo that Sigismund wasn't commanding the Imperial Fists at the Phall System. Later confirmed in Angel Exterminatus.
Properly Paranoid: Throughout his life, he could see the Eye of Terror in the sky, not matter what planet he was on, feeling as if it was watching him. He's incorrect that the Eye was watching him; it was the Chaos Gods.
The Resenter: Originally toward Rogal Dorn, but later damn near everyone.
Fulgrim and the Emperor's Children rank highly amongst the traitor legions, for good reason.
Shoot the Messenger: Cripples Berossus to the extent that he is forged into a Dreadnought afterwards.
The Spock: Noted as having a much higher emphasis on logic in all things, a trait shared by the rest of the Iron Warriors. Is also outright disgusted at how devolved the Emperor's Children and Fulgrim became during the Heresy.
The Strategist: He actively encouraged his men to consider how to assault AND defend the Emperor's palace from the beggining of the legion's inception. His attempt at defending it was competent and played out in a similar fashion to the actual defence later in the Heresy. His attack took far less time and incurred total enemy casualties.
"Well Done, Son" Guy: Got it from Dammekos but didn't want it, later wanted it from the Emperor and never got it.
The Warsmith's Grand company
The leader of the Warsmith's third company. Has not been named Captain despite holding the post for two centuries, due to his status of having some Imperial Fists gene-seed in with the his Iron Warriors gene-seed.
Black Sheep: Amongst the Iron Warriors, Honsou is pretty indifferent about the Legion and their legacy, which is why his actions are pretty atypical and he's practically indifferent to anything but his own desires.
Breakout Villain: Storm of Iron was written as a standalone novel, but Honsou quickly became a popular character, and one of Graham's favorites to write.
The Unfettered: The author describes him this way, as someone totally unbound by ethics and who doesn't give a damn about the consequences of his actions so long as he comes out of it better than he otherwise would.
Visionary Villain: Genuinely believes in the dream of Horus using the power of Chaos to unite humanity and protect it from Xenos threats. Of course, being a Chaos Marine, it's more along the lines of "subjugate humanity".
Brown Note: He's seething with so much Chaos, just looking at him causes nausea in his own underlings, and keeps an entire regiment of guardsman from being able to raise their weapons against him. It's because of his transformations.
Crazy-Prepared: At Hydra Cordatus, he probably had a hand in getting the Mechanicus infiltrator, which came about roughly a hundred and fifty years before Storm of Iron, and presumably built the hidden teleporter in the citadel which they used to infiltrate Cycerin in towards the end of the siege.
Crazy Enough to Work: His most well know plan involved: Finding a Tyrant Hive Fleet (this after the first Tyranid war but before the other hive fleets came to the Galaxy), stuffing it into a space hulk and wiring a Navigator into its controls and fired it right at Terra.