Britney is the half-sister of the hero Brit, as a young girl she was given an improved version of the serum that gave his half-brother his invulnerability.
During her first days as a superhero she battled her brother Euclid and enlisted in the army.
Invulnerability: Like her brother, Britney is invulnerable to all forms of damage, although she is considered to be slightly less durable than him.
Superhuman Strength: Britney possesses superhuman levels of strength, she is shown to be much stronger than her brother, she is strong enough to cause some pain to an alternate reality version of Invincible with her blows.
Decelerated Aging: The serum that turned her into a superhuman almost stopped her aging process.