The visual effects of the Rit Zien's kills became a memorable, albeit gruesome, highlight of the season.
The episode explores the vulnerability of the supernatural when forced into a natural world. [S9E6] Heaven Can't Wait
These were celestial medics who performed mercy killings on mortally wounded angels on the battlefield. On Earth, this angel has begun "mercy killing" humans who are experiencing even minor emotional distress. The visual effects of the Rit Zien's kills
Dean investigates a case in Rexburg, Idaho, where people are seemingly exploding into pink mist. He discovers that a "Ritual Man" (a Rit Zien angel) is responsible. On Earth, this angel has begun "mercy killing"
Now human and stripped of his grace, Castiel works at a "Gas-N-Sip" convenience store. He struggles with basic human tasks, such as cleaning toilets and managing a social life, under the alias Steve.
Castiel’s journey highlights the dignity found in "lowly" work. His pride as a former Seraphim is replaced by a genuine desire to be a "good" human.
The Rit Zien’s presence suggests that human suffering is so profound that even a celestial being can no longer distinguish between temporary sadness and a terminal soul-wound.