Infected Trinity Soldiers are enemies that appear in the Rise of the Tomb Raider Expeditions DLC Cold Darkness Awakened.
Infected Trinity soldiers are mutated humans, who were in contact with a gas, soviets developed decades ago, in Soviet Weapons Research Facility. The gas blinds humans, but it also enhances their hearing. Infected humans also have diminished intelligence, and are driven to murderous rage. Lara Croft speculated that the chemical alters dihydrotestosterone production, which is the reason behind it affecting primarily men.