In Wyvern Diary, Steve enlists at the age of sixteen and the lieutenant is twenty. In Fate of the Forty Sixth, Damian enlists at eighteen and a characters notes that one of his superior officers was a student of Steve’s mother and is about thirty. This would make her very young for a lieutenant colonel (too young by about ten years using averages from the US), as Steven is a firstborn son and people generally marry in their twenties in this universe (because having children earlier is weird and waiting until later doesn’t have the guarantee of pulse), making it unlikely that Steve’s mother is much older than forty. So there is a problem with Lieutenant Colonel Harris’ age and her rank. I will now give an explanation over my choice of character ages.
Years before the events of Wyvern Diary or Fate of the Forty Sixth there was a catastrophic war of unprecedented scale. Even back then, the private military contractors were using child soldiers, but the ages of officers were roughly equivalent to those of today. But the world, and the PMCs, were unprepared for the devastation the World War would cause and the destructive power of both sides. Must of the experienced officers died, were injured or retired during and after the war and this left many gaps in the Guild’s forces. So younger officers took leaps forward based on combat ability and rudimentary tests, putting inexperienced leaders in a high-stress and high-stakes environment. The jump-start promotions are still hurting the Guild, with basic errors being made due to the ineffective and sometimes neglected training. Most of these officers became glaring failures, but a few like Blayde and Harris managed to hold on and develop into decent leaders.
So if the ages seem a bit off, good. Because it’s like that after everyone better died fighting dragons and bio-technological beasts.