Brandon Bailey was the Chief Researcher and eventually Research Center Director of the Umbrella Africa Research Center. He worked closely with Dr. James Marcus in developing the Progenitor virus. They both traveled to Africa to study the Stairway of the Sun and Bailey was left behind in order to excavate and export the plants to Marcus who returned to Raccoon City. He would remain underground, working on Progenitor for another 30 years.
When the Research Center was finally completed, he took control of the operations there. After the Raccoon City incident, the facility was closed down, leaving Bailey without a job and purpose in life. He went on to detail in his diary:
And now the Research Center where I've spent half my life is closed. I really don't care one way or another. It's probably all for the best. Perhaps it is too late to have any semblance of a life again.
It is unknown if Bailey ever returned to a normal life, but according to Oswell E. Spencer's notebook, since he was one of the few Umbrella employees who knew of the Facility's existence, he was eliminated by unknown means.
He seemed good natured at one point but apparently after Dr. Marcus' death, he became cold, and emotionless.