Things have been pretty tense between Dean (Jensen Ackles) and Cas (Misha Collins) during Supernatural's final season, and it looks like their strained relationship will be tested again in Thursday's midseason premiere. In a sneak peek at the episode, titled "The Trap," the pair fail to see eye-to-eye over what to do about Sam (Jared Padalecki), who, along with Eileen (Shoshannah Stern), is currently with Chuck (Robert Patrick Benedict) after being tricked into a secret meeting.

Fearing that his brother might be killed or tortured, Dean proposes they drop everything and go after the floppy-haired Winchester. Cas, on the other hand, argues for sticking to their original plan to retrieve the Leviathan blossom in Purgatory for Michael's spell so that they stand a chance against the omniscient being, especially since killing Sam right now contradicts Chuck's grand ending.

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"Dean, just stop being so stupid," Cas asserts, checking the hot-headed Winchester for acting so rashly. It's Sam we're talking about, so it's understandable that he'd want to jump into action. However, Cas makes a good point about heading to Purgatory instead.

"That's the way we'll save Sam, and that's the way we'll save the world," Cas adds.

See how well Cas and Dean work together amid growing tensions when Supernatural returns Thursday, Jan. 16 at 8/7c on the CW.

Misha Collins and Jensen Ackles, <em>Supernatural</em>Misha Collins and Jensen Ackles, Supernatural