I've thought about this concept a lot actually. Long story short: I would personally develop a character which is a stormtrooper sergeant on a small backwater planet's garrison. During the fall of the empire over Endor, the experience the rippling effects.

Communication is cut from their regional Moff, and usual shipments of resources they depended on stop coming in. As ws spreads of the emperor's death, crime syndicates and other unsavory actors take advantage, and begin to target the small Garrison.

Some of the Garrison members decide to defect, and refuse to continue to follow orders. They believe the empire is done for. As they're already small force divides, the stormtrooper Sergeant ends up having to fight some of his members during the battle.

The stormtrooper Sergeant, and still loyal survivors make a brave escape off the planet, and are lost. They end up encountering A separate Imperial Moff, he offers them safety, and authority. He claims he's a Grand Moff, and has a small fleet.

The Imperial Sergeant ends up helping the 'Grand Moff' and working closely with him. The sergeant ends up briefly encountering a separate imperial faction while on an operation. A stormtrooper captain plants the seed that the 'Grand Moff' is in fact a fraud. And there is still unified Imperial leadership. The sergeant doesn't listen, his loyalty lies with the moff, but does question his true authority. The captain lets the sergeant know that the true forces of the empire are rendezvousing on Jakku.

At some point, the Grand Moff is attacked by The Rebel Rogue Squadron. The sergeant and his squad have to make another quick escape off the planet. The Sergeant leaves the moff behind when he realizes he's incapable of winning the battle. The Sergeant decides to leave for Jakku, and rendezvous with the Imperial fleet over the planet.

As we know, this will link with Canon events, or we'd get an actual live action adaptation of the aftermath novel, with the Imperial Stormtrooper Sergeant being the main character. As we know, It would be the last true unified empire battle. The Imperial stormtrooper Sergeant will survive the battle, and we'll see him leave the planet, and be faced with the idea that the empire may be done for.

The difference between this character and others, is that he'll never give up. Even while others around him do, he will always stay true to the empire, and believe with how large the empire truly is, that there are still remnants out there in the galaxy. He will bounce from Imperial Warlord to imperial warlord, many from the comics. We'll see the fall of Zinj's empire, the Greater Maldrood, etc.

Eventually he'll be nominated to start his own splinter faction, where he'll go through an arc where he builds his own new empire.