Rukio is one of two cubs born to Leo and Lyre, sibling to Rune. Physically, Rukio strongly resembles their mother, Lyre, mirroring her appearance. This contrasts with Rune, who closely resembles Leo. Rukio primarily shares narrative moments with Rune, frequently appearing alongside them. Both cubs become involved in schemes orchestrated by other characters, such as when Rick wins them over to his side during a conflict. These shared experiences highlight their roles within the family unit, though Rukio lacks individualized development or distinct story arcs separate from their sibling. Rukio remains defined by their familial relationships and physical characteristics.