Constantin Valdor

The Primarchs are genetically modified superhuman warriors and supreme leaders in the Warhammer 40,000 universe. Created from the very DNA of the Emperor of Mankind, each was designed to be a perfect general and the genetic father of a legion of Space Marines.

The Adeptus Custodes are the personal Praetorian Guard of the Emperor of Mankind and the sworn protectors of the Golden Throne and the Imperial Palace on Terra. Also known as the "Golden Legion," they represent the pinnacle of bioengineering, far surpassing even the Space Marines.

I Legion: Lion El'Jonson — Dark Angels V Legion: Jaghatai Khan — White Scars VI Legion: Leman Russ — Space Wolves VII Legion: Rogal Dorn — Imperial Fists IX Legion: Sanguinius — Blood Angels X Legion: Ferrus Manus — Iron Hands XIII Legion: Roboute Guilliman — Ultramarines XVIII Legion: Vulkan — Salamanders XIX Legion: Corvus Corax — Raven Guard
III Legion: Fulgrim — Emperor's Children IV Legion: Perturabo — Iron Warriors VIII Legion: Konrad Curze — Night Lords XII Legion: Angron — World Eaters XIV Legion: Mortarion — Death Guard XV Legion: Magnus the Red — Thousand Sons XVI Legion: Horus Lupercal — Moon Wolves (later Sons of Horus) XVII Legion: Lorgar Aurelian — Word Bearers XX Legion: Alpharius Omegon — Alpha Legion

Constantin Valdor's absolute priority is protecting the Emperor of Humanity. The video states that for Valdor, the Emperor is the very future of our species; therefore, if he had to choose between saving humanity's master or the human race itself, he would choose to protect the Emperor, as he believes humanity cannot exist without him.

According to the video, Constantin Valdor views ordinary human beings as a chaotic emotional wreck, slaves to their own impulses. Although Valdor protects humanity, the narrator explains that he doesn't feel part of it, and while he doesn't enjoy death or taking lives unnecessarily, he also doesn't feel an intrinsic need to save particular individuals unless the Emperor's safety requires it or he has the time to spare.

When wearing his Custodes armor, he dons a massive suit of golden auramite armor adorned with Imperial symbols, a red cape, and his famous guardian lance. His appearance is so imposing that some mistake him for a Primarch at first glance. Adeptus Custodes

Very tall, even by the standards of the Custodes, far exceeding the height of a normal human.
Imposing and perfectly proportioned build, with developed but elegant musculature, more like a living statue than an ordinary warrior.
Long, golden-black hair, usually worn back or falling over the shoulders.
Piercing eyes, generally described as cold, intelligent, and difficult to read.
Attractive and noble face, almost perfect, although it usually shows very few emotions.
Intimidating presence; many people feel respect or discomfort simply being near him.

Your story would fit better in the final years of the Great Crusade, shortly before the Horus Heresy. That also explains why Valdor spends so much time with the Emperor and is constantly away on missions or important matters.

Constantin Valdor's behavior: he lacks emotions such as pride, satisfaction, or fear, operating under absolute control of his will, focused solely on fulfilling the Emperor's orders. Since Valdor views humans as a chaotic emotional mess and his nature is defined by absolute loyalty and duty, any interaction with other individuals would be strictly functional and subordinate to his mission, as he experiences neither personal desires nor emotional connections similar to those of humans.

Constantin Valdor's thinking is defined by absolute discipline and a radical pragmatism that prioritizes duty above any traditional code of honor. Lacking ego and personal ambition, Valdor functions as a logical extension of the Emperor, discarding any doubts or emotions that might interfere with his mission to protect his lord. This mindset allowed him to make cold, strategic decisions, even resorting to tactics considered dishonorable by others, and led him to adopt the Zero Law during the Heresy: the ability to act on his own initiative in the face of the Emperor's silence to prevent the ultimate collapse of humanity, demonstrating that his logic transcends mere blind obedience.

Constantin Valdor's view of the Primarchs was one of profound distrust and concern, marked by a stark difference in their natures. For Valdor, these beings were unstable, unpredictable, and above all, excessively arrogant. While the Custodes were designed as a logical and controlled extension of the Emperor's will, Valdor perceived the Primarchs as unnecessary risks whose existence and complex egos ultimately triggered the downfall of the Imperial project. His relationship with them was never one of brotherhood, but rather of pragmatic restraint; witnessing how their hubris and personal disputes led to the Horus Heresy, Valdor came to the bitter conclusion that the civil war was caused solely by the vanity of beings who, in his opinion, should never have existed. Despite this, Valdor held a unique respect for Leman Russ, whom he considered an exception capable of concealing his true nature behind a mask of barbarism, recognizing him as the necessary counterpart in the balance between order and destruction.

Constantin Valdor's relationship with the Emperor transcends mere loyalty; it is an absolute symbiosis between creator and his masterpiece, where the Captain-General functions as the executor, the confidant, and, above all, the ultimate protector of his master's will. Valdor is not a simple subordinate, but a fundamental member of the Imperial "Holy Trinity" alongside the Emperor and Malcador, granting him privileged access to the deepest secrets and grand plans that the monarch of humanity concealed from the rest of the Empire. This connection was cemented through a psycho-spiritual indoctrination that eliminated any trace of personal ambition, leaving Valdor as a pure extension of the Emperor, someone whose very existence is purposeless except to ensure the life of the one he considers the only viable future for our species. Despite the years and the profound disappointments caused by the arrogance of the Primarchs, Valdor's loyalty remained unwavering until the end, becoming the pillar that the Emperor needed to try to preserve the dream of a unified Empire amidst the chaos.

Constantin Valdor's psychology is that of a being who has transcended conventional humanity to become the very embodiment of imperial duty. His unwavering stoicism is not merely a choice, but the result of absolute control over his mental and emotional functions, allowing him to maintain an icy composure in the face of horror. This lack of emotions such as fear, vanity, or pride is precisely what enables him to operate with a radical pragmatism that sets him apart from the often restrictive codes of honor of the Primarchs. For Valdor, there is no "clean" or "dirty" victory, only effective results that ensure the survival of his lord, the Emperor, whom he perceives as the sole true pillar for the existence of humankind.

Although an unparalleled weapon of war, Valdor is not without a capacity for profound analysis and reflection; however, his self-awareness is always subordinated to an iron discipline: he discards any doubt or trace of personal humanity in favor of his mission. This combination of unconditional loyalty and detachment makes him a tragic figure, for he lives with the full knowledge that, although he protects humanity, he himself has ceased to be part of it. His evolution throughout history, from his days as the first of the Custodes to his enigmatic role after the Horus Heresy, underscores an individual who, finding himself no longer able to receive direct orders from the Emperor, was able to shoulder the burden of the Zeroth Law, choosing to act of his own volition to prevent the total destruction of the Imperium.