Reinhard Tristan Eugen Heydrich entered the world on March 7, 1904, in Halle an der Saale, Prussia. His parents, composer and opera singer Richard Bruno Heydrich and Elisabeth Anna Maria Amalia Heydrich, provided social standing and financial stability through their music conservatory. Musically gifted from childhood, Reinhard excelled at violin and piano while demonstrating academic and athletic prowess, particularly in fencing and swimming. Youth brought bullying due to his high-pitched voice and persistent rumors of Jewish ancestry, despite his family's connections to Halle's Jewish community. Following World War I, at age 15, he joined Maercker's Volunteer Rifles paramilitary unit during civil unrest in Halle, though his involvement remained largely symbolic. He enlisted in the German Navy (Reichsmarine) in 1922, rising to first lieutenant by 1928. His naval career ended abruptly in 1931 when a court of honor discharged him for misconduct related to breaking an engagement. Influenced by his fiancée Lina von Osten, a committed Nazi, he subsequently joined the Nazi Party and SS. Heinrich Himmler appointed him to establish the Sicherheitsdienst (SD), the SS intelligence service, initiating his rapid ascent within the Nazi hierarchy. He later headed the Gestapo and Reich Security Main Office, organized Kristallnacht, chaired the Wannsee Conference formalizing the Holocaust, and served as Deputy Protector of Bohemia and Moravia. His brutal governance in Prague concluded on May 27, 1942, when Czechoslovak agents mortally wounded him; he died on June 4, 1942. Fictional narrative reveals his role as the Apoptosis (self-destructive factor) of the god Mercurius, granting innate supernatural abilities and a soul of exceptional quality. This connection induced a perpetual Sense of Foreknowledge – constant déjà vu from accessing memories across Mercurius's time loops – leaving him emotionally hollow despite achievements. In December 1939, as Gestapo chief, he interrogated clairvoyant Karl Kraft after an assassination attempt on Hitler. This encounter, coupled with breaking up a fight between future Longinus Dreizehn Orden (LDO) members Eleonore von Wittenburg, Beatrice Waltrud von Kircheisen, Wolfgang Schreiber, and Wilhelm Ehrenburg, prompted him to abandon self-restraint. He subdued the combatants easily and, with Kraft, founded the LDO, a secret society of thirteen members employing the soul-based magic system Die Ewigkeit to pursue godhood. During the 1945 Battle of Berlin, the LDO performed the Transmutation of Gold ritual to elevate him to godhood. Partially successful, his soul ascended to the extradimensional castle Gladsheimr, becoming a stockpile for millions of absorbed souls, while his physical body remained on Earth. For decades, he waited within Gladsheimr with his legion, the Einherjar – immortal warriors formed from souls marked by his Holy Relic, the Longinuslanze Testament. His goal evolved into achieving full divinity to destroy existence as an act of love, ending the predestination caused by Mercurius's loops. Physically, he stands tall at 210 cm, with pale skin, long blonde hair, and golden eyes, often clad in a military uniform bearing an LDO armband. Initially cold and emotionless – earning Adolf Hitler's epithet "the man with the iron heart" – his interactions with Mercurius and post-awakening state transformed him into a charismatic, philosophical figure. He expressed love for the world through a desire to destroy it, seeking worthy opponents to experience the unknown. His immense charisma commanded loyalty from psychopaths and serial killers within the LDO and could compel audiences to suicide to join his legion. He honored agreements and respected adversaries but displayed indifference toward his purported son, Isaak, calling him an "abomination." His powers derive from multiple sources. As Mercurius's Apoptosis, he possesses innate immortality (Types 1, 3, 4, 6, 8, 9) – he cannot permanently die unless Mercurius is killed – and superhuman physicality. His body itself is the Holy Relic Heilige Eolh, a near-impenetrable soul vessel with limitless capacity, shielded by barriers granting resistance to physical, magical, temporal, and probabilistic attacks. His primary weapon, the Longinuslanze Testament (Spear of Destiny), can only be wielded due to his supreme charisma. Merely viewing or touching it erases minds and souls. Its attacks always hit, always outpace targets, and inflict conceptual erasure across space-time, imposing a Stigmata that binds victims' souls to Gladsheimr upon death. His Briah (manifested craving), Gladsheimr - Gullinkambi Fünfte Weltall, materializes as a golden castle disconnected from reality. It draws in souls of the slain, adding them to his immortal legion, whom he can resurrect or whose abilities he can invoke. Upon reaching Atziluth (godhood), his divine law, Du Sollst - Dies Irae, elevates his entire legion to pseudo-god status, amplifying their powers conceptually. As a Hadou God, he embodies an abstract concept (destruction/love), gains omnipresence within his domain, reality-warping capabilities, and resistance to soul, temporal, mental, conceptual, and law manipulation. His destructive capacity scales to multiversal levels, affecting all creation. His narrative extends beyond his primary story. In the Marie route, he achieves true godhood but is ultimately defeated by Ren Fujii. Later, in Kajiri Kamui Kagura, he ceases to exist after Hajun kills Mercurius and Marie, as his existence is tethered to Mercurius. He is later revived alongside other gods by Naraka for unspecified purposes.