Legion

Legion is the name taken by the gestalt consciousness formed by 1,183 geth programs inhabiting a unique geth "mobile platform".

Legion is a unique geth mobile platform, designed to operate outside the Perseus Veil and interact with organics. To that purpose, it houses 1,183 geth programs, as opposed to the roughly one hundred found in other platforms, enabling it to operate independently and speak. In order to facilitate communication with organics, Legion possesses several panels on its "head" that move to simulate facial expressions. These flaps serve the same purpose as eyebrows in organics, raising to imply surprise or interest and folding forward (much like the furrowing of the brow) to show concentration.

It was created and dispatched following Commander Shepard's destruction of the Old Machine "Nazara", known to the rest of the galaxy as the Reaper Sovereign, investigating several of the worlds Shepard visited — Eden Prime, Therum, Feros, Noveria, Virmire, Ilos, and a dozen uncharted worlds. Eventually it found the Normandy's crash site on the planet Alchera, salvaging a piece of Shepard's N7 armor and incorporating it into itself to repair damage sustained on Eden Prime after being shot by Alliance soldiers. If questioned about specifically using Shepard's N7 armour to repair itself, Legion becomes evasive, first rationalizing that "there was a hole" and then stating "no data available" after being pressed. This suggests that the use of Shepard's armor was an irrational decision, which goes against the concept that every action the geth take is the result of calculation, unaffected by emotion.

Legion is first encountered while searching for the IFF on the derelict Reaper. It is surprised to find Commander Shepard (to whom it refers as Shepard-Commander) alive, but assists Shepard's team against the husks roaming the dead ship. Eventually, it is disabled by a husk while opening the way for them to reach the ship's mass effect core. If recovered, it can be sold to Cerberus for research (as intact geth are hard to come by), or brought aboard the Normandy SR-2 and stored under guard in the ship's AI Core. It can then be reactivated for Shepard to interrogate it.

When the geth does not appear to be hostile, it expresses its wish to help Shepard's mission, at which point it will join Shepard's team. When Shepard asks the geth its name, it simply states "Geth". Not satisfied, the Commander rephrases the question until EDI steps in and, referring to the number of programs active in the single mobile platform, quotes a passage from Mark 5:9 in the New Testament — "My name is Legion: for we are many". The geth accepts this to be an "appropriate metaphor" and is henceforth known as Legion.