The Winchester brothers are momentarily going their separate ways, and, as Dean hits the road, Castiel will be staying behind to watch over Sam in "First Born."

Following Crowley's (Mark Sheppard) expulsion of Gadreel from Sam's (Jared Padalecki) body during "Road Trip," the younger Winchester is harboring some negative feelings towards his brother and his decision to save him via angel possession. Meanwhile, Dean (Jensen Ackles) is convinced his very presence is toxic to the lives of those around him and, in an effort to keep his brother safe, he sets out on a quest alone to kill Gadreel (now portrayed by Tahmoh Penikett).

'Supernatural' Spinoff: Script Finished, Chicago-Based Series Backdoor Pilot Details Revealed [VIDEO]

When next week's episode opens, Cas (Misha Collins) and Sam will be esconded at the bunker while the former vessel continues to heal. Now that Cas has reclaimed his grace (well, not his, per se), the fallen angel will be missing something about human life, namely the taste of PB&J (see clip below). However, he will have time to develop a dangerous new plan to use Sammy as a means to track Gadreel.

Executive producer Jeremy Carver recently explained that, although Cas "made it" as a human and managed to survive in his new life, he was meant for something more.

'Supernatural' Season 9 Spoilers: Dean's Battles Enemies In Cain's Kitchen, Looks For A Way To Kill Abaddon [PHOTOS]; Sam Tracks Gadreel [VIDEO]

"This is a guy who, as nobly as he tried to become the best human he could, always very much had the understanding, whether he liked it or not, that he's intended for something bigger and greater. Some of us are just meant for a higher calling," Carver told TV Line. "Like Luke Skywalker could have been the best farmer he could have been, but he was meant for a higher calling. And Cas falls into this category of hero, as do the Winchesters. So it seems very apt that, at a certain point, he would come to this realization that he couldn't sit out this fight any longer."

Find out how Team Free Will fares in their quests when Supernatural airs Tuesdays at 9 p.m. ET on the CW. See a preview and promo photos of "First Born" by clicking here.