Shelley Maycraft is Leicester Maycraft's mother, yet her youthful appearance frequently causes confusion, leading others to mistake her for his older sister or girlfriend. She lavishes overt affection on her son, embracing him often and behaving in ways that imply romantic attraction, sparking recurring misunderstandings. Her playful, energetic nature extends beyond Leicester; she actively teases female members of Clan Oasis, particularly targeting Chelsea Arcot with remarks about her physique or skin tone, and sometimes gropes other women, though she curbs such actions in public.

Despite her predominantly lighthearted and comedic persona, Shelley demonstrates flashes of maturity and insight. She provides necessary guidance and support to others, counterbalancing her mischievous streak with dependable counsel. Her relationship with husband Nagan Maycraft receives less focus, though both engage in combat during pivotal moments, such as assisting the Tortilla sisters against a crystal monster.

Shelley primarily serves as comic relief within the narrative, often through exaggerated reactions to her son's interactions with women or her own antics. However, her presence also reinforces familial bonds, notably her connection to Minette, an automaton crafted by Nagan's associate, Mise Altoise.