EXCLUSIVE: As ABC and Marvel are prepping a spinoff from sophomore drama Agents Of S.H.I.E.L.D., I have learned that Season 2 cast additions to the mothership series Adrianne Palicki and Nick Blood are finalizing deals to headline the offshoot.

Palicki and Blood’s characters Lance Hunter and Barbara “Bobbi” Morse aka Mockingbird have quickly become fan favorites since joining Phil Coulson’s (Clark Gregg) team early this season. Lance is a quick-witted mercenary sharpshooter, while Bobbi worked undercover in HYDRA laboratories. Giving the spinoff a Mr. & Mrs. Smith vibe, Lance and Bobbi are former husband and wife who have let sparks fly in a push-pull relationship on Agents of S.H.I.E.L.D. Marvel, ABC and reps for Palicki and Blood declined comment.

The spinoff is supposed to be set up by events from this season of S.H.I.E.L.D. It is unclear whether that would involve the secret plan by Bobbi and Mack, which had been heavily teased going into the spring run of the show.

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The offshoot was developed by S.H.I.E.L.D. executive producer Jeffrey Bell and co-executive producer Paul Zbyszewski, who are writing the script and would executive produce. ABC is not expected to make a formal greenlight call until the script comes in, with the hope being to be able to do that before the upfronts. The spinoff may film a promo or do a pilot. If it goes to series, I hear Zbyszewski is expected to serve as showrunner.

The setup of the spinoff would allow it to air concurrently with S.H.I.E.L.D. The question is whether, following the decision to put Once Upon A Time and Once Upon A Time In Wonderland on the schedule at the same time, something ABC brass later officially regretted as likely damaging the spinoff’s chances — the network would do that again with S.H.I.E.L.D. Using the spinoff as a bridge between the fall and spring portions of S.H.I.E.L.D., which was the original plan for the two Once series, would make more sense.

The Agents Of S.H.I.E.L.D. spinoff is one of two new Marvel series for ABC in the works, along with a drama written by John Ridley, that, according to the latest online speculation, may be centered on Ms. Marvel (Kamala Khan). ABC and Marvel also have midseason drama Agent Carter in contention for next season.