User blog comment:4Ferelden/A new interpretation of Starchild's motivation./@comment-31.185.148.167-20120706100510/@comment-1679409-20120706154435

"...the harbinger was actually prothean indoctrinated, *probably* similar with what they were intending to do with the illusive man and the giant human reaper they were building in ME2..."

Harbinger can't be a Prothean-Reaper. The codex specifically states he's (it's?) the oldest Reaper stationed at Earth. Because the Prothean cycle was the most recently completed of countless cycles, he couldn't be a Prothean-Reaper and still be the oldest Reaper there.

I would actually like it better if your theory were correct, though, that Harbinger's personality comes from the personality of a particular indoctrinated Prothean. That would bring an interesting symmetry to the events of ME3 and may help explain why Harbinger can control the Collectors.