These are men that are trapped in cages, viewed by Lara Coft while she was exploring the Geothermal Caverns, in the game Tomb Raider (2013). The dark cavern is filled with rats, blood, bones and explosive natural gas. The Solarii call them "the unholy ones".
While Lara is trying to save Sam, she goes through the caverns to get to the Solarii fortress. She will witness Solarii men shoving a man into the cavern, where the prisoners swarm around him, committing cannibalism, if left alive they are hostile towards Lara. Here Lara will find documents that explain the events.
Mathias believed that the men would need to be strong of body, weak of will. Because of this, the new recruits are thrown into a chamber in the Geothermal Caverns and were left to fend for themselves for days, sometimes weeks, without water or food. Those who survived are welcomed with open arms. But at the same time, the recruits' humanities were destroyed, turning them into inhumane savages.
All the insane prisoners who are locked up have their own dialog. If Lara stands by their cage, without killing them, they will move and speak. The first one you're most likely come across will ramble to himself.
"Huh? What's that? A meal? More food." "Masters, so nice to me. More food to eat." "So nice. Maybe they will share." "Who's that? Who are you? (Aggressive) Who are you?" "Another meal. More food."
The next one will be leaning out of his cage, with his hand extended out. Obviously showing that he is nearly dead of starvation.
"Water, food... Anything? Please?" Then if you wait a second he will lower his hand "Just kill me then, woman." If you decide to raise your weapon at him, then he will say "Do it! Please. Kill me."
The next one will just be laughing to himself, the one opposite would be banging his cage aggressively to try and get you.
As you approach the next one, he will say,
"You! Stay away" and will run to the back of his cage, Saying at the back "This is my home!"
The last one, with the longest speech, will be muttering to himself, showing the player what had happened to him.
"Yes, yes, yes... A sailing trip... we were going around the world. What? I - I don't remember. With my wife… and my two daughters... two daughters. They were so lovely... But it's ok... it's ok. What? Oh... oh yes, yes. It came on us suddenly. Never saw a storm like it. Yes, yes, at night. Never saw the island... we woke to the wrecks. Shipwrecks... everywhere. Oh no, no, don't do that, stop... stop! Who were they? I don't know. Children of the Sun. Yes, they took them away... all three of them. I... I… no. I can't… no! Oh god... no! They killed them. I'll be with them soon, yes? Yes... In maybe weeks. Maybe days... yes. Yes, my love… With you soon… I'll be with them soon, yes?… Yes… Yes, my love. I'll see you soon…"
Sometime after escaping the Geothermal caverns, the player may find a set of relics at Shipwreck Beach; a toy train, a stuffed bunny plush, and a wallet containing a picture of the owner's two kids, where Lara will ask herself, what has happened to them? This could be related to what this prisoner says, showing the events that had been carried out.