Lost Soldier's Letter Home

Dearest Mom and Dad,

Life down in the mines is getting by. The Squad is as serious as ever. Everyone wears a grim expression. Carl said it's an "iron mask" issued by the higher-ups, and that wearing it is for my own good. I didn't understand at first, but after I saw what they did to the miners... I get it now.
If there's anything good to say about it down here, it's probably the stability of the daily routine. But that's not the whole story. A while ago, something seemed to happen in Mine No. 1. I heard yelling and the sounds of a fight. Could a Rock Serpent have gotten over there? Unfortunately, I was changing shifts that day, so I wasn't on duty there. I didn't see what happened.
But ever since then, the atmosphere seems to have gotten even colder. Carl's like a different person. He won't say a word, no matter what I ask him. But that's normal, too. After all, this is the Sislesa Mine. No one dares to say a single unnecessary word, and laughter is even more out of place.
It's just that sometimes, when I look into the depths of the mine, I can't help but wonder: in these bottomless mine tunnels, who really benefits? Who's happy here?
I don't really understand. I just know I have to wear this iron mask for another three months. In three months, I'll be home safe. Everything will be all right then.

I hope you are both well. Please don't worry about me.
— Your loving son, Allan