Saber's True Name is Fergus mac Róich (フェルグス・マック・ロイ, Ferugusu makku Roi?), the aspect of him as a child. Unlike other adolescent Servants, this form is not the result of a natural summoning. Scheherazade used her Noble Phantasm in conjunction with the power of Phenex to modify Fergus' Saint Graph to revert him to a younger age. Thinking his already massive libido would be increased to even greater heights with a younger form, allowing him to wreak havoc in the women-majority Agartha, Scheherazade accidentally made him much too young to care about such issues.
Agartha: The Mythical Subterranean SocietyEdit
When the Agartha singularity manifested, Fergus disappeared from Chaldea, ending up inside the Singularity. His Saint Graph was modified by Scheherazade's Phenex-enhanced Noble Phantasm and he was reverted to childhood before meeting with the group from Chaldea.
Fergus is unable to fight most of the enemies they encounter throughout Agartha, as the fighters are all women and he is reluctant to raise a sword against them. As such, he is delegated to protecting Ritsuka Fujimaru. He spends much of the journey lamenting his immaturity and lack of training, while enduring the teasing of his companions for not sharing his older self's love of women.
While he is not an active participant in the many battles, Fergus privately observes the values of Dahut, Assassin of the Nightless City, Berserker of El Dorado and even Rider of the Resistance as the rulers of their respective factions, hoping to learn how to best be a king. He initially fails to understand the logic behind Scheherazade's fear of dying, as it differs greatly from his Celtic warrior's mentality, but he volunteers to extend his protection to her as well.
His steadfast defense of Ritsuka eventually pays off, as Fergus is able to prevent Rider of the Resistance, by now revealed as Christopher Columbus, from fatally shooting the Chaldean Master following the defeat of Penthesilea. He is able to help fend off Columbus until Astolfo and Chevalier d'Eon are able to rejoin them, after which they defeat Columbus and Megalos, whom he had enslaved.
However, with the defeat of all the other Servants in Agartha, it is revealed that Scheherazade was the one who had partnered with a Demon God and is the mastermind behind the Singularity. As Agartha begins to float into the sky, becoming the flying island Laputa, Scheherazade explains her plan to Chaldea, noting that everyone fulfilled their roles perfectly except for Fergus, who was "miscast". Her intention had been to bring a younger Fergus to Agartha to wreck havoc with his libido, but he had ended up too young, making his current existence in the Singularity pointless.
- ↑ Fate/Grand Order - Agartha: The Mythical Subterranean Society, Prologue
- ↑ Fate/Grand Order - Agartha: The Mythical Subterranean Society, Chapter 1
- ↑ Fate/Grand Order - Agartha: The Mythical Subterranean Society, Chapter 15