User blog comment:Aleksandr the Great/Prothean Squadmate is Officially DLC/@comment-1221773-20120222035742

You're assuming the Prothean is 100% integral to ME3, though. Yes, he's obviously a very interesting character. Yes, he would have been better off included in the game. But if BioWare can compress him into separate paid DLC, there's a strong possibility that as interesting as he is, he isn't needed for the core story. He could just be a Prothean "average Joe" soldier, someone who can fill us in on Prothean culture and stuff, but who has no idea how to beat the Reapers. On the face of it, the situation wouldn't be much different than when we got Zaeed or Kasumi as DLC, or if you go into ME3 with a save file where Garrus and/or Tali died in ME2.