However, the demon refuses to disclose any information concerning the murders, choosing instead to reveal that Dean's wicked actions in Hell broke the first seal.

Alastair is eventually set free of his bonds when water damages the devils trap surrounding him and seizes the opportunity to attack Dean and Castiel, but is incapacitated and tortured by Sam, who forces him to admit that demons are not involved in the angel murders.

[5] The original breakdown released to the media described Alastair as a "calm and composed demon with a placid smile that belies his simmering sadism and evil.

"[10] Actor Christopher Heyerdahl deemed Alastair's lack of any goodness to be "what makes him so much fun", stating, "He just unabashedly loves creating havoc and pain and thinks it's the greatest thing.

[8] Writer Sera Gamble supported this characterization by explaining that Alastair, unlike other demons who have no experience with angels, is "exceptionally old and powerful, so he knows a trick or two".

[14] Although Alastair works with Lilith in breaking the 66 seals and trying to capture Anna for information on angels, Gamble felt that he would "rather be back in Hell, sticking bamboo shoots under fingernails", than starting the apocalypse.

"[13] Director J. Miller Tobin gave Rolston free rein over the character in "Heaven and Hell", but did "[reel him] back on occasion.

"[13] Overall, Rolston thoroughly enjoyed his time on the series, explaining, "Actors that play bad guys get to explore the other side of their personalities, things that you wouldn't normally have the opportunity or inclination to do.

[16] To honor the "music that [Rolston] brought," Heyerdahl developed what he describes as "a lovely three-way between what Mark had done, my own vision of the character, and the way director Steve Boyum played with the nuances.

"[18][16] Unlike Rolston, Heyerdahl insisted that he roll his eyes for Alastair's transition to fully white eyes—the visual effects department usually adds this in during post-production—because he "just thought it was kind of fun.

"[21] Rolston's "perfectly menacing" portrayal of the character continues in "Heaven and Hell," with Steenbergen making note of his performance as one that helped "save this episode from being more of a waste.

"[25] Steenbergen agreed that Heyerdahl did "an excellent job carrying on what Rolston started"—she wrote that he was "just as menacing and might even be a little creepier" than his predecessor—but was ultimately happy to see the character get killed off because she found his voice "fine in short scenes, but too over the top the more time that was spent with him.

"[28] Although she had viewed the decisions made to effect a Brando-esque voice for Alastair as "merely irritating in previous episodes," she believed that Heyerdahl's performance was "damaging" in the torture scenes of "On the Head of a Pin" as they were "campy to the point of being laughable," which "seriously undercut their dramatic power."