It's gotta be Rasputin speaking to the Exo Stranger in my opinion as well. Two little additional nuggets I saw: 1. The term "cousin". I've seen Exos use this term before. The vanguard quartermaster grimoire shows Cayde-6 calling Roni 55-30 his "distant machine cousin". So if a frame is a cousin to an Exo, then maybe Rasputin views the Exo similarly. 2. Rasputin's statement that you are not mine, though at some point you must have been. Reading vex 4, it shows it took a warmind to allow the Ishtar scientist to proxy into a mechanical body (think the movie Avatar) and keep their minds safe from the vex simulation they were once trapped in. If it took a warmind level intelligence to accomplish that, it must have also taken a warmind to run the deep stone crypt subroutine, which first gave exos human consciousness. By that rational, I view this as stating, because you (the stranger) are Exo, Rasputin must have at one point been involved (either himself or another warmind he has now taken control of) . But since the stranger can go "across" (move to alternate Timelines), she is not of his creation (ie: she learned new tricks). Which speaks to another theory about the FWC and the device, which is another topic for another day :)