Starting in the eighth season finale "Sacrifice", Crowley began exposing a "new emotional vulnerability" as a result of an unfinished demon-curing ritual performed on him in the episode and a resulting addiction to human blood in Season 9. On this topic, executive producer Robert Singer said that Crowley's secret enjoyment of his temporary sense of humanity influenced the character throughout the ninth season. However, a statement from Carver raised the possibility that Crowley might not retain this humanity in Season 10. Season 12 revealed he occupied his throne as "King Of Hell" because the prince of hell next in line for the throne, Ramiel, has no interest in the title. He gives Crowley the throne under one condition: that he be left alone, forever. Ramiel lived a solitary life fishing until one day, the Winchesters and Castiel go kicking up that nest. As Cass was dying from being impaled with the Lance of Michael, Sam Winchester defeated Ramiel with the Lance of Michael. Crowley saved Castiel by breaking the Lance, therefore breaking the spell the Lance of Michael carried. Maureen Ryan of "The Chicago Tribune" disclosed in her October 9, 2009 review of fifth season episode "Fallen Idols" that "the ubiquitous and talented Mark Sheppard" had been cast as the "pivotal" demon character Crowley in the upcoming episode "Abandon All Hope...". Sheppard had previously worked with "Supernatural" producer and director Kim Manners on "The X-Files". Sheppard revealed in an interview with "Variety" on November 11, 2014 that he and Manners had discussed the possibility of Sheppard appearing on "Supernatural", but that Manners had died before Sheppard ultimately landed his role as Crowley. In the same interview, Sheppard also revealed that when reading the script for "Abandon All Hope", he "got the giggles" and took the part partially to honor Manners and partially out of appreciation for the work of writer Ben Edlund, as Edlund had written for "Firefly", another show on which Sheppard appeared. In an exclusive interview with Michael Ausiello on July 15, 2010, series creator Eric Kripke confirmed that Crowley would return in the show's sixth season. Knight felt that "Crowley's journey on the show has been a bold and ambitious one". On the Season 9 subplot of Crowley's human blood addiction, he wrote that it was "one of the most interesting and unexpected subplots of [the] season...and it left a lasting (and often amusing) impression on viewers."