Blood Angels - Blood Angels' Flaw: Every Space Marine Chapter is defined by the legacy of their Primarch. Through their gene-seed these mighty beings would shape their sons' bodies, while through teachings and philosophy they would influence their minds. Yet none amongst the Primarchs would have as profound an effect upon their progeny as did Sanguinius. Although it is known to but a few, the Blood Angels and their Successor Chapters are a dying breed, for they suffer from a dreadful genetic flaw.This Chapter, once the most golden and blessed of all the Chapters of the Adeptus Astartes, now shuns the company of its fellows where possible. Some Blood Angels, it is said, are driven by a terrible death-seeking madness called the Black Rage, brought on by visions of the death of their Primarch. Others are afflicted by the terrible Red Thirst, a craving for blood which some claim may be the first signs of corruption by Chaos. It is known that some amongst the Blood Angels themselves spend much time seeking a cure for these conditions, although most have resigned themselves to the slow and terrible decline of their Chapter.Some savants say that it is because Sanguinius was more touched by Chaos than the other Primarchs during his gestation capsule's flight through the Warp after he and his superhuman brothers were stolen from the Emperor's gene-laboratory. They cite the fact that he possessed wings -- an obvious mutation -- to support their case.Their argument runs that the gene-seed that was extracted from him was genetically flawed and corrupted even before the first Blood Angels Space Marines were created from it by the Emperor, and thus terrible consequences were preordained. Other savants of the Astartes deny this, citing that the Emperor Himself trusted Sanguinius implicitly, and personally oversaw the creation of the Blood Angels. Certain Heretics counter this with the argument that the Emperor also once trusted Horus above all others in His Imperium, and that even He could make mistakes...Other Imperial scholars claim that the Flaw lies in the process that is used to create each new generation of Blood Angels Astartes. They assert that it has crept in through the generations because the Blood Angels use the process known as Insanguination to activate the implanted gene-seed organs within their Aspirants. All Space Marine Chapters use the gene-seed organs to unleash and control the metabolic processes that transform an ordinary mortal into a Space Marine.The gene-seed is encoded with all the information needed to reshape ordinary human cell clusters into the special organs Space Marines possess in those instances where they are not directly implanted after being cultured in vitro. The gene-seed contains genetically-engineered viral machines which rebuild the male human body according to the biological template contained within it. However, even from the beginning of the Astartes' existence, there was never a set way to activate these functions of the gene-seed.During the First Founding of the 30th Millennium when the Space Marine Legions were first created, the process was still highly experimental and many different ways of controlling and managing the transformation from mortal into Astartes were tried. This led to the Space Wolves using the ritual known as Blooding, the Imperial Fists using the process known as the Hand of Faith, the White Scars conducting the Rites of the Risen Moon and the Blood Angels using the ritual of Insanguination.The process of Insanguination was originally triggered by injecting the Aspirants with tiny samples of their Primarch's own blood. This practice, of course, ended with the tragic death of Sanguinius at the hands of Horus during the Siege of Terra. However, some of his blood was preserved within the Blood Angels artefact known as the Red Grail. The still-living blood could not be kept this way for long and so it was injected into the veins of the Sanguinary Priests. In this way they became living hosts to the power of Sanguinius. To this day, the drinking of the collected blood of the assembled Sanguinary Priests from the relic called the Red Grail is part of the induction ritual for all Blood Angels Priests as well as the Chapter's Aspirants.It is from these Sanguinary Priests that blood is taken to trigger the transformation of Aspirants into Space Marines. It is possible that over the countless generations since the time of the Horus Heresy the cells within the Blood Angels' gene-seed have mutated, slowly at first but more quickly in recent years, and that cumulative errors in DNA replication have resulted in the Flaw. Whatever the reason for the Flaw, it is certain that its hold over the Blood Angels has become ever stronger, and their tendency towards self-destructive insanity greater. Unless it can be halted and reversed, the Chapter and all of its successors among the Sanguinary Brotherhood are doomed to extinction.The Flaw of the Blood Angels has also been attributed to a combination of the genetic defects in the Legion's Omophagea gene-seed organ implant, and the psychic disturbance created during the final seconds of Sanguinius' life. During the battles of the Horus Heresy on Terra and Mars, the stored gene-seed imprint of the Blood Angels was lost, forcing the Legion to have to extract the gene-seed needed for their reconstruction after the Heresy from the fallen body of their Primarch himself. Every Space Marine created from the gene-seed drawn from Sanguinius after his death was doomed to fall to the Flaw, and in the 10,000-year history of the Legion and its Second Founding Successor Chapters, only three Space Marines have managed to defeat the Black Rage once it manifested (Chief Librarian Mephiston (twice) and Brother Rafen -- both with the assistance of visions of Sanguinius, and the Librarian Ashok of the Angels Sanguine).