Obsessed

Obsessed is an achievement in Halo: The Master Chief Collection. It is awarded for activating the thirteenth Halo 2: Anniversary Terminal on The Great Journey. The achievement is worth 5 Gamerscore and can be unlocked on any difficulty.

Location
The terminal is in the back of one of the jail cells from which you free the Sangheili High Councilors and Mgalekgolo. It is in the center right cell on the upper level.