The eldest of the Stall family, Dwight was the ideal first born; smart, athletic, outgoing, the perfect son. When his sister was born he became the greatest of big brothers as he did when their younger brother was born. That was at least until the youngest was old enough to become jealous, then things went downhill for their relationship.
When he joined the Army, Thomas followed. When he was offered to try out for the G.I. Joe team, Thomas followed. While he made the team his brother vanished without a trace. He blamed himself. If he wasn't on an active mission he was at a bar nursing a whiskey.
When zombies began walking the Earth, he went to his family home, only to find his parents being feasted on by flesh-eaters. He killed them all in an alcohol-fueled blacked-out rage. His sister found him while the ichor of the undead still clung to his skin. His younger brother found them later. He offered a choice, "Join or die." He joined.