Brave New Verse
A former Alliance soldier, Petra found Ethan on Ezra where he was killing citizens of a local township: Midian. After the situation was de-escalated, it was revealed that everyone in the town was infected with White and Ethan was attempting to put them down before they could become Reavers. He himself was also infected, but his mutation granted him more time than the rest of the villagers.
Petra managed to secure a cure for her crew and the citizens of the town, then took XA out to hunt down and kill the super Reaver which was infected with an airborne strain of White. XA and Petra put the creature down, and much to Ethan’s relief no more lives were lost. Ethan is still decimated by the experience, having previously completely wiped out a town before he arrived in Midian.