Early in Hal's life, his mother died and his father and re-married. This new family union gave him a step sister: Emma Emmerich, and the two became very close. Over the years, Hal became seduced by his step-mother and they had an affair. When his father discovered this, he committed suicide in their swimming pool, attempting to take Emma with him. Emma expected her brother to save her, but he was with his step-mother at the time and did not realize. Surviving, Emma became estranged from Hal, and he ultimately runs away from home because of his perceived failures.
After going through college, Hal is employed by ArmsTech where he becomes the lead designer on Metal Gear REX.
Being a huge fan of Anime, Hal takes the name Otacon, which is short for Otaku Convention.