Recruitment: Legion

Recruitment: Legion

If you want to have the Geth from the Reaper ship as a member of your squad, head down to the AI Core (located through the Medical Bay on Deck 3) immediately after acquiring it and reactivate it. The Geth explains that there are some Geth known as 'heretics', who worship and cooperate with the Reapers in order to attack humanity and other races. On the subject of a name, EDI pops up and suggests Legion, because there are in fact 1,183 Geth intelligences inside the body in front of Shepard.

Note that to be able to do the Legion loyalty mission before the mandatory mission triggers (you can still do it after, but with a heavy price to pay), you must talk to him about his problem now, and accept it, before doing anything else!