Legion

"We do not experience fear, but we understand how it affects you."

Legion is a geth that has learned to think on its own, separate from the neural network. It marks a "natural evolution" of the geth, who are normally tied to groups in order to maintain sentience, having developed the ability to operate independently and even speak. It bears a gaping hole in its right chest cavity.

Legion is voiced by D.C. Douglas

Geth Infiltrator
Geth Infiltrator is Legion's class power.

Dossier
Legion is obsessed with Commander Shepard, even going so far as to have a piece of Shepard's discarded armor incorporated into its own. Shepard must eventually confront Legion to find out why it is hunting Shepard. It is discovered that the geth are at odds with each other and Legion is part of a faction that opposes the Reapers which it calls "the Old Machines" and refers to the ones who follow them as "heretics". Eventually, it joins Shepard's team for the mutual interest of defeating the Reapers and the antagonizing Geth. Still, understandably, Tali is at odds with Legion and becomes resentful towards Shepard for recruiting it.

Legion's Appearance
Legion presented an opportunity to develop the basic geth design by adding moving parts that allowed it to animate with detailed expressions. Originally added to the concept just for fun, Shepard's N7 armor became an integral part of Legion's appearance and back story.

Trivia

 * Legion's name is given to it by EDI who suggests the biblical passage "My name is Legion: for we are many". Legion acknowledges it is a fitting metaphor, as it describes itself as a geth mainframe or representative.
 * Legion was the first character seen in any Mass Effect 2 media, appearing in the teaser trailer.