Samara/Morinth

Two possibilities exist: Either Samara killed Morinth, or Morinth killed Samara. Only Shepard knew the true answer, as only she was there at the fatal moment. Regardless, that was the past, and in the present someone claiming to be Samara was onboard the Normandy and serving loyally enough. Whoever she was, she was refined, elegant, beautiful, and still wearing the uniform of an Asari Justicar, a uniform which left little to the imagination. However, rumor and suspicion don't simply disappear, and sometimes they might just be true.

Even if the truth is hard to believe, and dangerous to share.