Thousand Sons - Red Orders: In addition to the core structures of the Legion, there were three orders which existed both within and beyond its circumference. These "Red Orders" stood apart from the Legion's Fellowships and their circles, and indeed the cults of Prosperine psychic lore, their membership crossing such divides. Their purpose was not the practice and ascendency of psychic mastery, for that was the purview of the great cults, not the day-to-day tactical oeprations of the Legion, but rather they were macro-military structures. Perhaps as much an outgrowth of the traditions and culture of the Legion as a deliberate structure, they were made to cope with the wider factors of the conducting of the Great Crusade, the furtherance of the Legion as a whole and its relation to the wider Imperium.Order of Ruin ("The Unmakers") - Known by the symbol of a poised serpent, the Order of Ruin were a sect of mystics said to be obsessed with numerology and the hidden structure of the universe. Calculations, logicians, analysts and organisers of supreme ability, the Order of Ruin were the siege makers, logistical specialists and planners of the Thousand Sons. When the Legion deployed its armour and ordnance to lay waste to a city or break a planet's defences, it was the formulae of the Order of Ruin which guided the number, placement and timing of shells, explosives and force. It is said that the Order of Ruin knew the strength of every warrior and war machine within the Legion, and weighed them all in calculations that only they and their primarch understood. When a force was raised for a campaign, the Order of Ruin would be in the background assisting by arcane means in the determination of the disposition and strength of that force. The arraying and maintenance of the Legion's warships also fell under the Order of Ruin's hand, as did the creation and supply of all its materiel. Perhaps unsurprisingly, the Order of Ruin also maintained the closest contact with the Mechanicum, in particular with the isolated Forge World of Zhao-Arkhad, which the Legion had liberated and with which it had maintained many binding ties afterwards. Under its general command laboured all of the Legion's forge-masters and Techmarines, many of which came directly from within this order's ranks.Order of the Jackal ("The Measure of Life and Death") - The Order of the Jackal had a presence in every other structure and faction of the Thousand Sons, including the other Red Orders. The role of this small order was twofold: to remember the dead and to raise the next generation of warriors for the Legion. The grave urns of the dead kept beneath the pyramids of Tizca on Prospero were tended by their hands, and it was in the memories of each member of this order that the deeds of the fallen were held. When a warrior on the edge of death was considered for the honour of internment in the iron embrace of a Dreadnought, it was the Order of the Jackal who weighed his worth and decided his fate. To them also fell the task of assessing and selecting aspirants for induction into the Legion. On Prospero and many other worlds, they would walk amongst the gathered throngs of potential recruits, testing with their minds and casting divinations of their fates. In this way, the Order of the Jackal were the guardians of the Legion's past and future. The Legion's Apothecaries, who also were all but indivisible from the Order of the Jackal, maintained the Legion's gene-seed and were but a practical manifestation in some ways of the Order of the Jackal's wider purpose. In their role as protectors of the Legion's traditions, the Order of the Jackal served another highly important ritual position as arbiters within the Legion, as their members within each of the Five Cults formed the guardians of each cult's temple; their dual allegiance and responsibility marked by their ceremonial jackal-masked helms and emblems alongside the symbols of their cult.Order of Blindness ("The Hidden Ones") - It is only by extrapolation, and the interpretation of scraps of intelligence, that the wider Imperium knows of the existence of the Order of Blindness. Thought to have been headed by Magnus' equerry, and former tutor, Amon -- the so-called "Hidden Ones" appeared to have been an order of infiltrators, spies, interrogators and scouts deployed to gather intelligence. How the members of this order were recruited, controlled and deployed remains unclear, though there is evidence that the use of psychically-conditioned non-Legiones Astartes Humans were a part of their broader methodology. An operative of the Hidden Ones would infiltrate a target organisation of interest to gather intelligence while operating under a cover so deep that they never even realised that they had been psychically-reprogrammed to act as a sleeper agent for the Thousand Sons. Beyond this, their membership and purpose remain shrouded, though there is some evidence that the order may also have been responsible for the control of certain fringe military elements within the Legion, whose purposes were less to do with stealth than the creation of chaos in a foe, such as the Thousand Sons' few Destroyer-type units, although this remains unconfirmed. The Hidden Ones' status following the Thousand Sons Legion's transformation into a Chaos Traitor Legion devoted to Tzeentch and the enactment of the Rubric of Ahriman is unknown.