Supernatural's Bartholomew has been earmarked as a villain, but there may be more to his past than viewers know.

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When Bartholomew (Adam Harrington) returns to the CW drama in "Captives," the fallen angel will have a heart-to-heart with Castiel (Misha Collins). Considering old Barty's involvement in the Buddy Boyle scheme, many fans might be anticipating a hostile exchange between Cas and his kin. Their cordial greetings, however, will probably spark confusion.

"We see in the promo that Bartholomew gives Castiel a greeting that the audience might not necessarily have thought was appropriate. It's a smiley, happy greeting. In another promo we actually hear Castiel say his only choice was 'to obey or be killed' People will find out what he's actually talking about when they watch the episode but there are some high stakes happening," Hatttington explained to Screen Spy, adding, "We find out why he's so emotionally invested. We also discover more about his relationship with Castiel and how they know each other."

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Now that the angel war is heating up, Castiel will soon have to choose a side. Collins has referred to Bartholomew as more malicious and sinister than previous angelic villains but that doesn't negate the fact that he may chose to align with him against Metatron (Curtis Armstrong) and Gadreel (Tahmoh Penikett) .

Perhaps Cas' final decision will hinge on who/what the "unforgiven" is and how they/it will play into the conflict.

"The other thing [about "Captives"] is that the audience will learn more about Castiel. It's what's really cool about this episode in particular," Harrington told Screen Spy. "There are actually a lot of hints in the trailer. They reference 'the unforgiven.' We learn a little bit more about what that means. Not what it is, but what it may be referring to."

What is Castiel really up to? Find out more when Supernatural airs Tuesdays at 9 p.m. ET on the CW. Click the video below to see a preview for the series' next episode.

Tags: supernatural the cw television