Siegbert is the son of Xander and the cousin of Forrest, as well as one of the two paternal grandsons of Garon. Like the other children of Fates, Siegbert was placed in the Deeprealms to keep him safe from the war. Siegbert became particularly close to his father and would spend his days learning all he could from swordsmanship to penmanship in an attempt to impress his father whenever he would visit. He also would regularly receive news of his father's efforts in the war. In his Paralogue, Xander pays his Deeprealm a visit. Although Siegbert is happy to see his father, Xander's visit is interrupted by invisible forces that have been invading his realm constantly as of late. Siegbert rushes off to battle the enemies as Xander follows close behind. Xander notices that they appear from the water pools around the forest which the invaders are coming from. After utilizing all Dragon Veins in the forest to stop the invasion and routing those already present, Xander notices that this is not the first time Siegbert's Deeprealm has been attacked and asks why he did not notify him. Siegbert tells Xander that he believed that by fighting off the invaders on his own, he could prove that he was worthy of being Xander's son. Xander is proud that Siegbert took on the responsibility to fight off the invaders without Xander having to teach him to do so. Xander asks that Siegbert be comfortable with telling him anything on his mind. Siegbert asks if he can join Xander's army, stating that he can now fight alongside him to help Nohr. Xander warns Siegbert that the enemies on the battlefield will be much more dangerous then the ones they had just dispatched, and allows him to stay in his Deeprealm if he wants to. Siegbert is unfazed by Xander's grim message and readily joins the army.