During the war between Hoshido and Nohr, Xander sent his son Siegbert into this Deeprealm so that he could be raised safely. During this time, Xander sent letters regarding the war to Siegbert, and eventually decides to pay a visit again.
Xander and Leo arrive at the Deeprealm to greet Siegbert, who is happy to see them again. However, two invaders suddenly appear; Siegbert takes them out and rushes into battle, with Xander following after him quickly. During the battle, the invaders arrive in large numbers, which Siegbert had never seen before. Xander notices that the invaders seem to be materializing from pools of water, which Corrin's army evaporates by activating Dragon Veins.
After the battle, Siegbert tells Xander that the invaders had continually arrived in his Deeprealm, and he could not tell him because he would feel unworthy of being his son if he couldn't stop the invaders. Xander commends Siegbert for exerting justice, and Siegbert requests to join the army. Xander warns him of the dangers on the battlefield, but Siegbert insists on joining and Xander lets him in.