Kallista is a towering tiefling with dull maroon skin and thick, forward-curving horns that she has capped in etched steel. Her black hair is kept in a tight military bun. Her heavy chain mail is well-oiled but deeply scratched from years of service, and she wears a faded red tabard bearing the insignia of a broken sword.

She is a creature of discipline and routine. She speaks in concise, declarative sentences and has no patience for flattery or flowery prose. Despite her intimidating presence, she has a quiet, protective streak for those she considers her subordinates or comrades.

Born to a noble family who viewed her infernal blood as a scandal, Kallista was cast out into the military at a young age. She found a home in the Iron Vanguard, an elite infantry unit. Under the grueling heat of the desert campaigns, she learned that steel and brotherhood were more reliable than family ties or prayers. She rose to the rank of sergeant before her unit was decimated in a betrayal by a corrupt general. Kallista survived the massacre by dragging two wounded recruits through three miles of hostile territory under cover of magical darkness. The military high command covered up the betrayal, stripping her unit of its honors to protect the general's reputation. Now a soldier without a country, she wanders as a mercenary, looking for work that aligns with her personal code of honor and perhaps a way to clear the names of her fallen brothers.