When he was still young his father left the Navy as Senator Palpatine dissolved the Republic and became Emperor. The family settled on Alderaan, where Aaron briefly flew Y-Wings with the Alderaan Militia before Senator Organa dissolved it.

The Gregory family grew up in an isolated section of Alderaan's hill country, and Lewis grew up tall and strong from the physical labor he was put to. A good student, he was also a good athlete, learning boxing and martial arts in his teenage years. Lewis always wanted to pilot starfighters, but his father, veteran of many campaigns that saw horrendous loss of life, insisted that he study engineering instead. His grades were good enough to get a scholarship to the University of Briggia. Unfortunately, the day he left for University was the day the Death Star arrived over Alderaan.

The transport carrying Lewis and several other students off-planet was stopped and seized by an Imperial stormtrooper platoon, and the teenagers were forced to sit and watch their homeworld be destroyed by Grand Moff Tarkin and his battle station. The platoon commander secreted the students away for his own purposes; all but two were sold into slavery. Lewis and a girl named Lasa were kept and taken to the troopers' permanent base, in a backward section of the planet Malkan.

Lewis was turned into a "moose-boy", trooper slang for a menial servant and punching bag for the platoon. Lasa was kept as the platoon commander's personal consort. After two years of abuse and debasement, Lasa sacrificed her life to cause a diversion that allowed the newly-christened "Moose" to escape. He hid away in a truck convoy headed to the spaceport. Stealing some mines from the truck he was hiding in, Moose caused a diversion by blowing up some of the trucks, and successfully escaped into the seedier depths of the city.

Moose succeeded in finding a smuggler that would carry him off-planet, but the same smuggler then attempted to deliver him back to the garrison. In a battle inside the spaceport, Moose succeeded in killing the troopers and "convincing" the smuggler to take him to Correllia. Once they were in space, however, the smuggler tried to kill him to collect a small death mark. After a firefight, Moose ejected the smuggler into space; the ship was damaged, though, and dropped out of hyperspace in the midst of the Alderaanian debris field. The smuggler's transport was crippled when it bounced off a couple of asteroids, and Moose drifted with the derelict craft for four weeks, surviving on rations and bare minimum life support, until he was picked up by an Alliance Frigate.

The Alliance didn't believe his story at first, and while it was being checked out he was sent into the infantry. There, he was one of only three survivors of the massacre of the Ten'see IV garrison. After that, he was sent off to pilot training, with a specialty in heavy assault. He graduated and joined Blue Squadron's 19th Tactical Bomber Wing, and then moved on to command Buccaneer Squadron before joining White Squadron as a B-Wing pilot, until he became Wolfshead Squadron's Officer of Operations.

Moose is a big guy--193 cm tall, 110 kg, blonde hair, and blue eyes. He is an excellent athlete, in top physical condition, and reasonably skilled in boxing, karate, and swordplay. Despite a jovial, wisecracking personality, he is a fiercely driven pilot that spends as much time in the simulators and in the cockpit as possible. He loves to attack large ships--the bigger the better--and although he likes his B-Wing, his favorite fighter is the accurate, stable Koensayr Y-Wing. With his biological family completely destroyed in the Alderaan massacre, the pilots of Wolfshead Squadron have become his only family.