Kelly-087 was born Kelly Shaddock on the human colony of Imber in 2511. In 2517, Kelly was abducted by the Office of Naval Intelligence and conscripted into the Spartan-II Program. Kelly quickly became known for her particularly fast sprinting speed, running faster than even all her highly-trained Spartan teammates. She fought throughout the Human-Covenant War, working mostly as a member of Blue Team under the leadership of John-117. During the rescue of her, along with other Spartans and Doctor Catherine Halsey from Reach following its destruction, Kelly received severe burns over most of her body, requiring significant medical attention to fully recover. Using this as an excuse to get Kelly alone, Doctor Halsey sedated Kelly just prior to the Massacre at Eridanus Secundus, taking her onto a commandeered ship and leaving with Kelly to the planet Onyx.
Having been brought to Onyx against her will, Kelly inadvertently became involved in the Onyx Conflict, becoming reunited with Fred-104 and Linda-058 soon after on the planet’s surface. Kelly continued to fight as a member of Blue Team with Fred-104 as the lead through the last days of the war and during the post-war era, eventually reuniting with John-117 in 2557. Blue Team continued with their old leader after John’s return to the UNSC, fighting in many conflicts throughout the galaxy.