'Supernatural''s own post-Olympic return this past week with "Captives" definitely moved the CW drama's ninth season pace forward a few notches, but it can't outrun the casting of spinoff 'Supernatural: Tribes'. 'Heroes' alum Danielle Savre and 'Vampire Diaries' vet Stephen Martines are the latest to join the 'Tribes' crew, but what new monsters can we expect to see?

Via TheWrap, Savre joins the Chicago-set spinoff as Margo, the acting head of the shapeshifter Hayden family, an ex-punk rocker-turned-corporate professional who feels threatened only by the return of her prodigal brother David ('Vampire Diaries' star Nathan Buzolic) into the family. Martines will play Detective Freddie Costa, a world-weary Chicago cop who acts as a mentor to  leading man Ennis (Lucien Laviscount), but is also on the payroll of one of the powerful monster families.

Set amid the various families, 'Supernatural: Tribes' focuses on Ennis Roth, who puts his police academy training to use as a monster hunter after his fiancée is killed in the crossfire of the monster war dominating Chicago. The tragedy leads him to discover the truth about what lurks in the shadows (we'd expect from Sam and Dean) and become a monster hunter himself. The only character yet to be cast is that of Violet Durant of the werewolf Haydens, who herself has eyes toward forbidden love with David.

‘Supernatural’ writer Andrew Dabb will pen the script, executive producing alongside Eric Kripke, Robert Singer, showrunner Jeremy Carver and McG. Singer will also direct the pilot, which will air as a backdoor pilot in the 20th installment of the current ‘Supernatural’ season.

Whether or not 'Tribes' will move forward with the mothership 'Supernatural''s 10th season this fall is anyone's guess, but what say you? Are you apt to see what the 'Tribes' have in store?

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