The trail leads back to the AW version of Kaia Nieves (first introduced in the Wayward Sisters backdoor pilot), who possesses a powerful spear that previously managed to wound Michael.
The third episode of Supernatural ’s 14th season, titled "," primarily explores Dean Winchester’s internal guilt and the physical aftermath of his possession by the Alternate World (AW) archangel Michael. Key Plot Developments
Much of the "useful write-up" on this episode focuses on Dean’s self-loathing. Critics from The Winchester Family Business highlight that while Dark Kaia’s battles are external, Dean’s are internal—he struggles to forgive himself for being "only human" and vulnerable to Michael's trickery.
After Michael mysteriously leaves Dean’s body, Sam and Dean team up with Castiel and Jack to find a weapon capable of killing an archangel.