Rell was one of a number of children aboard the Zariman Ten-Zero during the ill-fated voyage that created the Tenno. Unlike the other children, Rell found it difficult to identify emotions and would be overwhelmed by too much sensation. His mother Kay, another passenger aboard the Zariman, loved him dearly and worked patiently with him to manage his difficulties through a variety of tools, including a deck of cards with various faces drawn on them to help Rell identify emotions, or a humming, tuning-fork-like device called a "Donda" to help Rell focus his thoughts and deal with the sensations of sound, color, and touch which sometimes overwhelmed him. Kay was also unfortunately forced to defend Rell from the other children aboard the Zariman, some of whom mocked his afflictions.