Agent Joseph Fierro was a member of the Winslow Accord and part of Commander Jacob Hendricks' team. The team consisted of John Taylor, Dylan Stone, Alice Conrad and Javier Ramirez Once Fierro, Stone, Conrad and Ramirez learned of the illegal experiments by the Coalescence Corporation, they defect from the WA to the Common Defense Pact and are hunted down by Hendricks and Taylor.
On June 2nd, 2064, Fierro and his comrades were sent to investigate the abandoned Coalescence Corporation headquarters in the Singapore Quarantine Zone, due to the activity of the local criminal syndicate, the 54 Immortals, triggering a distress signal inside the facility. There Ramierez and his comrades discovered a CIA black project known as SP/CORVUS, which was an illegal human test program that had inadvertently caused the Singapore disaster which killed 300,000 people.
The CIA could not let this knowledge become public and planned to kill Fierro and the rest of his team, planning to call the team back to a black station and then assassinating them. However, Stone's team caught wind of the plan and slaughtered the black station staff first. Stone and his team then planned to defect to the Common Defense Pact while also hunting down those responsible for the program. They were pursued by John Taylor and his own team. In Egypt, Stone's team discovered Yousef Salim, a behavioural psychotherapist who worked on the black project and kidnapped him. He was subsequently interrogated and executed by Stone and his team. However, Taylor's team soon caught up with them. While Stone and Fierro were able to escape, Conrad was captured and killed. The two fled to the Sub-Cairo Aquifer, under the protection of the Nile River Coalition, to plan their next move but were once again pursued by Taylor's team. While Stone was able to escape, Fierro was captured, interrogated and executed by Taylor and his team. This distressed Hendricks substantially.
Ultimately, every member of Fierro's team would be during the manhunt, leading Taylor being critically injured, and Hendricks doing hostage rescues instead of wetwork.