Billy Rabitson was an old friend of Chris Redfield. The two had been in the same class at school together, and while Chris spent most of the time in the Principals office, Billy received straight A-grades.
The two parted after high school. Billy was selected to join the Massachusetts Institute of Technology while Chris joined the US Air Force.
Upon graduating, Billy joined Umbrella Pharmaceutical, Inc., a well-known drug company famous in the area, but secretly researching into and developing Bio-organic weaponry. The two reunited in Raccoon City, where Billy worked at a local Umbrella building and Chris worked in S.T.A.R.S., a police unit funded through donations by the company. Eventually, Billy's work had gotten him moved to the Chicago offices.
Upon leaving Raccoon City on a jet, it made an un-scheduled landing where it dropped him off. The plane then took off again and crashed near the Arklay Mountains. Billy's death certificate was signed after his corpse was reported to have sunk to the bottom of a lake.