Solarii Brotherhood

The solarii Brotherhood are one of the enemy's that are encountered in Tomb Raider (2013)

Spoilers alert When Mathias arrived on the island, as his fellow survivors died trying to escape the island, he knew their was something more to the storms. As he was discovering the secrets of the island, he found that he could not do it alone, he gather a small group of loyal followers. Beleiving they must understand power and the need to organise. But more importantly, they cannot hesitate to kill or use violence, making it their Life there. This began the brotherhood of solarii, by giving them structure, purpose and work.

After explaining the truth of the island, he would offer the survivors a choice: death or salvation. Who opposed would be immediately be killed. Women would be sacrificed to the stormguard or would be used in their ceremony to find the Sun Queen successor. Mathias recruited as many as possible, choosing those who are physically strong, but not too smart, so they would fall in line and take orders. Those who questions would be killed immediately. He drafted laws and a code for them to live by. They would need to prove their commitment to the queen, making them fall in line and believe.

The Solarii built a city near the Queen's palace while Mathias searched for the key to unlocking her power and escaping the island.

Initiation
As stated by a Solarii in one of the Confessions of a Solarii entries, 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 foods. Those who survived are welcomed with open arms. But at the same time, the recruits humanities were destroyed, turning them into inhumane savages.

The lack of food and water caused most of the recruits to resort to cannibalism, wasting no time tearing apart the new ones and eat them, as witnessed by Lara after escaping from her captors. Some recruits are also locked in cells, their sanities slowly dissolved into insanities.