From Halopedia, the Halo wiki
The Triad is a human religion founded by the self-proclaimed guru Dasc Gevadim. The followers of the Triad believe that everyone harbored three internal lives, and believed one can reach spiritual "transcendence" by linking the three.
The founder Dasc ran many seminars through video feeds until he disappeared. These videos received many purchases and the religion gained millions of followers. When Dasc disappeared, many believed he had reached transcendence when in reality he had left to Beta Gabriel under a false identity. During the Jiralhanae occupation, he was captured and placed in captivity. He managed to escape with UNSC linguistic expert Connor Brien, however he felt that he could not let the secret of his continuing existence be revealed. Thus, Dasc killed Brien with his own M6 sidearm and hid from the UNSC reinforcements which arrived soon after, preferring that one man die so that the faith of millions could be preserved.
By 2558, Triad followers were still active in their beliefs spreading it around on Waypoint. After the emergence of the Guardians on several human colonies, Dasc Gevadim resurfaced to preach that the Forerunner constructs' awakening would precipitate a spiritual transcendence for his followers, claiming to have willed himself back to the material world to spread this message. Gevadim and a group of Triad followers were on Laika III when Maya Sankar, Black-Box, Mshak Moradi, and Bostwick crashed on the planet and were subsequently taken to the Triad cultists' camp. Shortly after their arrival several members including Gevadim began to float off the ground due to a gravitational anomaly that usually preceded a Guardian.
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