User blog comment:Cory Jaynes/Reapers origins/@comment-188.61.41.2-20110801194719

IMO, the Protheans became the Collectors, because the Reapers were somehow unable to turn them into a Reaper or Reapers. The Collectors may have been comparing their DNA to humans to discover why they were modified and indoctrinated, while humans are being harvested.