Byleth Eisner/Synopsis

The story of the Ashen Demon Byleth Eisner.
==Background==
Byleth Eisner is the child of Jeralt Reus Eisner, the former captain of the Knights of Seiros, and his wife, Sitri. They are the ultimate product of Saint Seiros' millennia-long efforts to resurrect her mother, the goddess Sothis.
Sitri was an artificial being created by Seiros under the alias Rhea to act as a vessel for Sothis; while Sitri proved to be a failure, she was raised by Rhea as her own daughter. Byleth was born without a pulse, causing Sitri to beg Rhea to save her child's life; Rhea did so by transferring Sothis' heart to them. As a result, Sitri died and Byleth had no heartbeat and never laughed or cried; Jeralt, fearing Rhea, took advantage of a fire to flee the Church and went into hiding.
Jeralt and Byleth spent the next two decades wandering the continent as mercenaries. Due to Byleth's strength and skill in battle and emotionless demeanor, they eventually earned the nickname "Ashen Demon".
== Fire Emblem: Three Houses ==
==== Part I (White Clouds/The Academy Phase) ====
Byleth rescues the nobles Edelgard von Hresvelg, Dimitri Alexandre Blaiddyd, and Claude von Riegan from a bandit attack, awakening Sothis within them and earning the attention of the Church of Seiros. They are taken to Garreg Mach Monastery, where Rhea reinstates Jeralt as a Knight of Seiros and grants Byleth a post as a teacher at the Officer's Academy. Byleth chooses one of the three lords to teach and spends the next year opposing the mysterious Flame Emperor in their efforts to destroy the Church. During one of their time with the house of their choosing, the house leaders begins to reveal their disdain for the Crest System.
* The Crimson Flower Route: Edelgard reveals her hatred of the Crest System, believing it to be the root cause of the corruption surrounding the land of Fódlan. 
* The Azure Moon Route: Dimitri believes that the Crest System shouldn't be the only way to measure someone's worth. While he acknowledges the importance of the Crest System, he also recognizes its flaws.
* The Verdant Wind Route: Claude wants to know more about the Crest System and the Heroes' Relics, from their origins to their importance. 
Eventually, an assassin murders Jeralt; an enraged Byleth pursues her into a forest, but is lured into a trap and banished into a dark abyss. Sothis sacrifices herself to grant Byleth her full power, allowing them to escape. In the aftermath, Rhea takes them to the Holy Tomb to receive a divine revelation, but they are attacked by the Flame Emperor, who is revealed to be Edelgard. If Byleth chose the Black Eagles and accepted an invitation to witness Edelgard's coronation as emperor of Adrestia, they have the option of defecting to her side; otherwise, they remain allied with the Church. Edelgard attacks the monastery and defeats Rhea, and Byleth is injured and sent into a coma for the next five years.
==== Part II (War Phase) ====
If Byleth sided with the Church, they awaken to find that Rhea has been captured by the Empire, the Holy Kingdom of Faerghus has been reduced to a puppet state, the Leicester Alliance is fractured between pro-Imperial and pro-Church factions, and the Empire is on the verge of conquering all of Fodlan. Byleth raises an army to battle the Empire, with the exact details depending on which house they chose at the beginning. After a brutal three-way battle between the Empire, Kingdom, and Alliance known as the Battle at Gronder, Byleth invades the Empire, besieges the capital Enbarr, and kills Edelgard. If they chose the Blue Lions, the war ends here; Rhea appoints them to succeed her as Archbishop as the Church of Seiros, and they help Dimitri lead Fodlan into a new golden age. If they chose the Black Eagles or Golden Deer, Edelgard's vassal Hubert warns them about the true masterminds behind the war, "those who slither in the dark". Byleth invades their stronghold and defeats them. After defeating either Rhea after she suffers a draconic degeneration-induced mental breakdown (Black Eagles) or Nemesis, an ancient warlord (who killed Sothis and slaughtered the Nabateans) resurrected by "those who slither in the dark" as a last act of spite against Fodlan (Golden Deer), they unite the continent as the first ruler of the United Kingdom of Fodlan. If the Golden Deer were chosen, Byleth and Claude, who becomes the king of Almyra, form an alliance and open up Fodlan's broders, ending the continent's isolation from the outside world.
If Byleth sided with the Empire, they awaken to find that Rhea and the Church of Seiros have been granted asylum in the Kingdom, which has fought the Empire to a stalemate. Byleth and Edelgard lead Imperial forces and conquer the Alliance to eliminate them from the war, either killing or exiling Claude in the process. After beating back a counterattack by the Knights of Seiros and killing a high-ranking member of "those who slither in the dark", Byleth and Edelgard invade the Kingdom and kill Dimitri. Rhea retreats to the Kingdom capital of Fhirdiad and orders it burned to the ground to slow down the Imperial advance and kill Byleth, but Byleth finally slays her. After Rhea is killed, Byleth collapses as their heart stops beating. However, the Crest from their heart vanishes, causing it to be able to beat again. Though in exchange, Byleth loses Sothis' power and goes back to being a normal human, as their hair and eyes turn back into their blue color. They then turn their attention to "those who slither in the dark", defeat them, and help Edelgard lead Fodlan into a new golden age.
== Fire Emblem Warriors: Three Hopes ==
In an alternate timeline from Three Houses, Byleth and Jeralt's mercenaries face rival mercenary Berling's forces during a job. Byleth almost single handedly wipes out the opposing force, including Berling herself, except for a young mercenary named Shez. Before Byleth can kill them, Shez is given a mysterious power by a being named Arval, but even with this new power, they are still no match for the Ashen Demon. Eventually, Jeralt orders his forces to withdraw, their job completed, at which point Byleth calls off their fight with Shez and leaves. Shez vows to become stronger until one day they will be able to defeat the Ashen Demon.
Following the timeskip, Byleth and Jeralt, joined by Alois, are hired by the factions that oppose Shez's during the war. During one encounter, Sothis awakens and takes control of Byleth's body, overpowering Shez and causing them to flee. Before Sothis can give chase, Byleth resists her and regains control of their body.
=== Defeating the Ashen Demon Path ===
In the next encounter between Byleth and Shez, the player's actions have a large impact on the story; if Shez focuses on fighting Byleth, they ultimately kill Jeralt; Sothis once again takes control of Byleth and kills one of Shez's allies in retribution (Randolph in Scarlet Blaze, Rodrigue in Azure Gleam, and Judith in Golden Wildfire). Sothis convinces Byleth to give her complete control of their body in order to avenge Jeralt, with Byleth leaving Jeralt's mercenaries under Alois's command. In the penultimate battle, Sothis appears and attacks Shez, only to discover that she does not fully control Byelth's body as she believed. This allows Shez to gain the upper hand and ultimately kill both the Ashen Demon and the goddess inhabiting them, though they find no relief or fulfillment in the deed and lament on how things could have gone differently.
=== Recruiting the Ashen Demon Path ===
If Shez instead focuses on their main objective and ignores Byleth, they surrender alongside Jeralt and Alois and are recruited into Shez's faction. Before the final battle, Arval, in reality a vessel for the soul of Epimenides, suddenly possesses Shez and attempts to kill Byleth; before they can land a killing blow, Shez resist them and urges Byleth to flee. When Epimenides regains control of Shez, he continues his pursuit of and attempt on Byleth's life, only to be interrupted by Shez's allies. Following Epimenides defeat, Byleth holds no ill will toward Shez, recognizing that they were not in control of their actions.
Category:Synopsis