Following its transformation into a garden world by the Traveler, Mercury was inhabited by humanity during the Golden Age. At this time the planet was covered in grasslands and trees with pink leaves. During the Collapse, the Vex undid this transformation and completely changed mercury into a Machine World within days of their arrival. The mysterious Cult of Osiris has many refuges on Mercury, the last known location of their idol.
During the Red War, Mercury was partially consumed to fuel the Red Legion’s star-destroying superweapon, the Almighty. Nearly a third of its mass is free floating, no longer attached to the planet itself.