Note: the history below is inferred from the translated description of his backstory, and may not be entirely accurate.The Frontier has long been a place seen by many as a land of opportunity, but also one of lawlessness. Many of the region's occpuants chose to engage in a life of piracy and other criminal activities, making the Frontier a very dangerous place to live. The increasing adoption of Titans by these criminal elements, unable to be stopped through conventional force alone, led to the creation of the Mk.6 Automated Law Enforcement Officer (ALEO) and AL-6 - using combat data based off other IMC Pilots.
During the Battle of Demeter, AL-6 piloted a Destroyer-class Titan, and was able to survive the battle successfully. Following the battle, AL-6 has exceeded expectations in tracking down, destroying and apprehending outlaws. Unlike many of the other robotic combatants employed by the IMC, his designers intended to create a guardian of the Frontier rather than a simple mindless automaton - to help this goal, AL-6 is outfitted with a unique core designed to help learn 'human' attributes.
AL-6 operates on one main principle; Robots do not tolerate human dangers. AL-6 is a defender of those he sees fit to protect, and will go to extreme ends to hunt down "dangerous forces" on the Frontier.