Diane, the Serpent’s Sin of Envy, is a Giant with a complex, centuries-spanning history. Disdaining her clan’s conflict-driven ethos, she departed at a young age, crafting rock golems for companionship. Her path soon crossed with an injured, amnesiac fairy king whom she nursed to health, forging a bond that endured centuries until he erased her memories to shield her, prompting her return to the Giants’ Clan.

Trained by warrior chief Matrona, Diane refined her combat prowess while rejecting her people’s violent traditions. When Matrona sacrificed herself to save Diane from Holy Knights, Diane faced wrongful imprisonment before being rescued by Meliodas, who drew her into the Seven Deadly Sins. Initially nursing unrequited feelings for Meliodas, her jealousy toward his bond with Elizabeth softened into enduring friendship. Fragmented memories of her past with King eventually resurfaced, rekindling their connection.

Endowed with a Giant’s immense strength, Diane commands earth manipulation via her magic, Creation. Her war hammer Gideon, weighing 998 kilograms, amplifies her abilities to upheave terrain or conjure quicksand. She temporarily hardens her body into metal for defense and employs techniques like Lightning Rod to absorb and redirect electricity, proving pivotal in clashes against the Ten Commandments and the Demon King during the Holy War.

Post-war, Diane succeeded Drole as Giant King, cementing her leadership. She married King, uniting Giant and Fairy clans, and bore seven children. Four inherited fairy traits, remaining human-sized, while others exhibited Giant heritage. This followed her use of Merlin’s shrinking medicine, depleted through multiple pregnancies.

Diane’s journey epitomizes self-acceptance and resilience. Once isolated by her size and societal rejection, she embraced her dual identity as a gentle yet formidable leader. Her evolution from conflicted exile to revered matriarch and warrior underscores her ability to harmonize compassion with the demands of power and legacy.