Varangian - Pilot
Soren Holmgren's family on Rasalhague was not historically involved in the ongoing resistance against the principality's Kurita conquerors. His father was an officer worker, while his mother painted landscapes. But then the Coordinator of the Draconis Combine was assassinated in 3004 by a Rasalhague nationalist, and as punishment, random executions were ordered. Soren's father was one of those so punished, destining Soren for a lifetime dedicated to striking back at House Kurita.
As soon as he finished technical school, he volunteered for the Rasalhague liberation guerrillas. They further trained him in covert operations focused on repositioning military hardware. Stealing BattleMechs is far more technical than merely piloting them, requiring both skills and specialized hardware. Soren excelled at it, substantially reinforcing the armories of the liberation guerrillas, while maintaining a cover as a quiet vehicle mechanic.
But these things never last forever. Eventually, you get discovered. The Rasalhague resistance force was grateful enough to get Soren and his remaining family off-planet. Now, his family resettled on a Periphery world, he works as a mercenary pilot, preferentially seeking out contracts against House Kurita, so he can continue his vendetta.
Can be found as a random starting pilot or in hiring halls.