Slayde is an enemy character in Fire Emblem Gaiden. His role was greatly expanded in the remake. He is 32 years old. Many years prior to the events of Fire Emblem Echoes: Shadows of Valentia, Slayde was a minor soldier in the Zofian army of noble descent. One day, he was summoned to a discreet location by Desaix who tasked him to kill the royal children of Lima IV in order to further his downfall from grace. Slayde agreed to the task and burned down the Villa that housed them. To the public, there were no survivors of the Villa fire, though rumors had spread that princess Anthiese may still be alive. Nevertheless, the tragedy he orchestrated him boosted him in rank in Desaix's guard, becoming captain.

While on patrol near the southern end of Zofia, Slayde and a few cronies stumbled upon Ram Villagewhere he encountered several children playing in the forest nearby. After threatening the children to bring him and his men food and lodging or else have their village destroyed, Slayde notices that one of the girls, Celica, bore a striking resemblance to princess Anthiese. Before he is able to abduct her, Mycenmakes a timely appearance and repels Slayde. Unfortunately, the discovery of Anthiese's location forces Mycen to take her to Novis Priory for her safety. Years later and after King Lima IV's death, Zofia not only was dealing with the impending invasion of the northern nation of Rigel, but also insurrection within its army, splintering into two separate factions; one lead by Desaix who aspires to keep his current seat of power over Zofia and a small band of former knights of Zofia who wish to wrest control from Desaix. The group called themselves the Deliverance.

Slayde continues to serve as Desaix's captains and reencounters the Ram Village children, minus Celica, now fully grown and members of the Deliverance. At Zofia Castle, Slayde is among the many soldiers stationed there to defend the castle. During the battle, Slayde helps to set up a double so Desaix can escape the castle when the battle swings in the Deliverance's favor. After the battle and shamed for the loss, Slayde encounters some Duma Faithful near the castle grounds. The Duma Faithful take Slayde to Rigel where he seizes the opportunity to join the Rigelian empire, providing valuable information of Zofia to Rigel. For his information, he is assigned as the captain of the Final Bastion of Rigel Castle.

After a long grueling war, the Deliverance make it to the Final Bastion where they encounter Slayde. Prior to the battle, Slayde personally greets the Deliverance and explains his rise to power in Rigel. Clivechastises him for being nothing more than an opportunistic coward, even selling out his homeland for power. Slayde in a huff orders his forces to attack the Deliverance. Ultimately, his forces are overpowered and Slayde is killed.

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