On one of their earlier adventures, the Diggers sisters, Gina and Britanny "Cheetah" Diggers, fell under a curse that would get progressively worse until it killed them. To escape the curse, Gina put a copy of her and Cheetah's biological data into an inert mass of organic matter and sent the curse after it. The plan worked, mostly. While the curse no longer followed Gina and Cheetah, it's energy brought the organic matter to life and made it evil. The being called itself Grave Digger and immediately sought them out to kill them. The sisters held her off until Dr. Diggers arrived and removed the curse while the being remained. Grave Digger became Brianna Digger and a member of the family.
Brianna was originally a straight combination of Gina (though not quite as smart) and Cheetah (though not quite as powerful), but has developed her own personality. She has a passion for high-tech weaponry, a thirst for danger and adventure as well as an innate propensity for magic not shared by her sisters (Cheetah eventually gaining artificial ability in that area). Physically speaking, while she is the combination of a werecheetah and a human, she lacks the werecheetah transformation ability. Instead, her normal 'human' form has most of the attributes of a werecheetah such as superhuman speed, strength, rapid healing, and improved senses at half the level of a transformed werecheetah. This is only visually apparent in her cat-like ears and the stripe she has over one ear.
Her greatest achievement in technology is the creation of the 'Peebo' series AIs, robots who's personality and learning capability surpasses that of any invented by her sister, and who even possess an aura, suggesting she instinctually pours her magic talents to aid in their creation. Peebri, Peegi, and Peebrit, or the 'Peebo scouts,' are the smartest and lead Peebos in this series, used as assistants and modeled after her and her sisters. Brianna treats the advanced learning AIs much like daughters, which in a sense, they are.
After several years, she trained to harness her magical powers under her archmage father, often combining it with her skill in firearms when in combat for a variety of effects, whether using her powers to energy weaponry or enscribing magic glyphs with her carefully-aimed shots.