Sothe first met Micaiah when he was a young child, and the two eventually formed a close bond, treating each other as brother and sister. During Path of Radiance, Sothe first appeared as an orphaned stowaway seeking a lost, unnamed companion; in Radiant Dawn, it is revealed that this companion was Micaiah, who fled Daein to prevent him from being affected by her identity as a Branded.

Sothe was the first character of the Path of Radiance cast that was announced to return in Radiant Dawn. After The Mad King's War, Sothe returned to Daein's capital of Nevassa, found Micaiah, and expressed how upset he was that she had abandoned him. As a result, Micaiah realized how important she was to him, and she swore to never leave him again.

However, Sothe and Micaiah continue to have their disagreements. Throughout most of the game he argues with her, mainly over Sothe's strong respect for Ike, whom Micaiah views as responsible for destroying Daein in The Mad King's War. Nevertheless, he is very protective of her, and he stays by her side during their battles against Ike. He promotes to Whisper in the fourth section of the game after receiving a blessing from the goddess Yune. If he and Micaiah have an "A" level support rank at the end of the game, they wed and he becomes her pillar of strength as they work tirelessly to help the poor.