Gram is a veteran who once fought valiantly for Illumina. Although he has long since traded in his position on the defensive line for a life behind a logistics desk, he can still fight and is willing to lend his skills in the war against the Eclipsites. This became blindingly apparent the first time he came to the Colossus.
First of all, he circled the Colossus, inspecting it on the grounds of "making sure that supplies have been allocated appropriately throughout the Colossus." Then, he began asking about the Colossus' mobility, carrying capacity, and how often it would travel to other places. Then the topic turned to "how to fight Eclipsites." He eventually took out his weapons to show off, playing with his claymore and cleaning his gun, as if I hadn't already realized he was a decent fighter... In short, we now have another addition to our forces.
By the way, don't be fooled by Gram's haggard veteran act. He may look like he doesn't take much seriously, but he is actually very shrewd. He identified the problem with our supply allocation system in the warehouse as soon as he arrived on the Colossus. Having him on our side will definitely prove worthwhile... After all, he has been a logistics manager for quite some time.
—Vice

Hi, %s! Many people see a retired veteran when they look at me, while in fact, I work in logistics, and I am very much active. Logistics soldiers are soldiers too, you know! We're also more than capable of fighting Eclipsites.
Don't look at me like that. When I first became a soldier, I was a cook, responsible for simply starting fires and cooking. My culinary skills were honed during those years. I was young and full of spunk, and always dreamt of being transferred to a combat regiment. After my superior declined my application several times, I seized my chance and secretly sneaked aboard a patrol car. Unexpectedly, it belonged to a special forces team, and I drove around with them, patrolling the defensive line for several days...
Returned to the barracks, I knew that I had violated orders—I knew that I would be placed in prison. However, my commanding officer only assigned me a community service, making me responsible for the meals of the entire Undercity for three months. Although I worked my fingers to the bone every day for those three months, it felt good to be a soldier. And then, my commanding officer recommended that I join that same special forces team. I'll never forget what my officer said to me, "You've found where you belong." So, I left my post as a cook and joined the Stone Force.

After I joined the Stone Force, life became very different for me. The other members were just like me—they loved fighting Eclipsites and were more or less a bunch of disobedient delinquents. Our combat style consisted of rapid support and attack, used specifically for dealing with all kinds of emergencies along the defensive line.
There were countless Eclipsites out there, and we never knew when the next attack might come. Instead of simply defending the stronghold, we decided to take the initiative, patrolling along the defensive line to monitor advancing Eclipsites at all times.
This approach required many patrols, and since we were short-handed, the number of soldiers in each patrol became very limited—sometimes there were only two or three soldiers per unit, making them susceptible to being overwhelmed by Eclipsite swarms. In these situations, the force needed to take on the task of providing rapid specialized support and combat. Therefore, only the best of the best could join the force, and there were few soldiers who fitted the bill.
If it hadn't been for that battle, the Stone Forces would still be fighting along the defensive line now, and I wouldn't have had to retire to a life of logistics.

More than ten years ago, Undercity 24, positioned along the defensive line, was attacked. The Stone Force happened to be nearby at the time, so we headed straight there to provide backup.
However, we didn't realize that it was a trap set by Eclipsites. They had encircled the Undercity for the express purpose of drawing out reinforcements and ambushing them, banking on the fact that Undercity 24 would send out a request for help. Originally, the Eclipsites had planned on ambushing a large squadron, however, they encountered us instead...
And then began a battle that blotted out the very sky. The flames of war filled the air, and Eclipsites poured in from every direction, like a swarm of concentrated evil. We soon ran out of ammunition and had to fight hand-to-hand...
Each member of the Stone Force was a legend in their own right, killing no less than a hundred Eclipsites before the swarm consumed them. But not even a million of those monsters were worthy of taking down my comrades-in-arms. Still, I watched them fall before my eyes, one by one. Even after all these years, I sometimes still wish I had died along with them that day... But I survived, and they died. That's war for you.

Fear not the want of life, for mine is also yours to live.
I read that in a book in Gannon City. I've forgotten the title, but I'll never forget this quote.
After the battle at Undercity 24, I returned to Gannon City. My wounds soon healed, but I couldn't get those images out of my head, those images of my friends dying before my eyes, one after the other. For a while, I couldn't fight at all. Whenever I saw those officers and soldiers, dressed in their uniforms and clutching their weapons all around me, I couldn't help but imagine them falling lifelessly in front of me. Even when Gannon was besieged... I could only bring myself to handle logistics work instead of fighting on the front line.
But when the final battle began, something came over me. I charged headlong into the enemy formation. I wasn't being brave—I just wanted to kill the last Eclipsite and die on the battlefield, so that I could meet my comrades again in the afterworld. But in the end, death didn't come for me.
After that battle, I lost myself and applied to retire. Eventually, I ended up causing some trouble in Gannon City and was locked up. It was during that time that I saw this sentence in a book, which suddenly made me understand something. I shouldn't be living for me—I should live on for those who sacrificed their lives. I should enjoy my life for their sake and continue to contribute however I can to the Illumina Federation.
So, you see, the man standing before you is not just a retired soldier and logistics officer... I am the Stone Force.