I want to keep this short, because I'm lazy and don't want to write up a full topic, just get some discussion going. I'll probably end up adding to this later. There are several pieces of evidence that lead me to believe this. - Ghost: "The Vex are returning home. Something is calling them back to the Black Garden." - Ghost: "It's like the Vex have dormant networks underneath every planet, just waiting to be revived" - Grimoire Card: Mercury "Legends say that Mercury was once a garden world. Now its surface, baked in the Sun's glare, is honeycombed with forgotten Vex structures. No life stirs here. Not anymore." - Grimoire Card: Venus "Here and there a line of light marks where ancient Vex spires, thought long-dead, have once more been energized." - Final Boss encounter: Sol Progeny. Children of Sol, Eschaton, Imminent and Primeval What are the implications of the Vex originating here? Did they travel outside of our solar system? Did they return during the collapse, or were they simply awoken during or after it? Were they hidden inside the black garden, and the Darkness opened and thus unleashed them?