After meeting Legion in the Reaper IFF mission. A Geth attack will disable it, and you will decide to take it back to the Normandy.

Choice: Activate or Sell Legion¶

After meeting Legion in the Reaper IFF mission. A Geth attack will disable it, and you will decide to take it back on the Normandy. Once you’ve finished the mission, and you get back on the Normandy, you’ll be talking with Miranda, and Jacob about the fate of Legion, this’ll give you the choice to give it to Cerberus (sell), or talk to it first (activate it).

Choice: Activate Legion¶

You’ll find Legion in the AI Core room, which is found just past Dr. Chakwas in the Medical Bay. When you go in there, you’ll find it, at the back, laying down, and inactive. Head over to it, and tell the guard you’re activating it, and EDI will isolate the ships systems from it just in case. By activating it, you’ll gain Legion as a squad mate, and it’ll allow for the chance of a peaceful resolution in the Geth/Quarian storyline in Mass Effect 3.

Choice: Sell Legion¶

If you decide to give Legion to Cerberus, you’ll gain 50,000 credits, and 20 Renegade points, as well as an e-mail from the Illusive Man, congratulating you for your decision. That’s the good part… By selling Legion, in Mass Effect 3, it’ll be impossible to get a peaceful resolution in the Geth/Quarian storyline, and you’ll lose one of the biggest boosts to War Assets as well. These can have major ramifications on the ending there as well, finally, you’ll encounter it as an enemy too! For Mass Effect 2, you’ll lose a squad mate, and the loyalty mission that comes with it.