Identity crises abound in the mirror universe
"Into the Forest I Go" was an hour that brought a lot of pieces together in this uneven first season of Discovery, and it ended with a final twist that we now see serves as a sharp left turn into a new arc set in Trek‘s Mirror Universe. The MU was of course famously established in TOS‘s "Mirror, Mirror," before lying dormant for decades until DS9 picked up the mantle for its annual hijinks. Then in its final season, Enterprise also ventured into the arena with "In a Mirror, Darkly," which featured some time-bending that brought the USS Defiant back from the TOS era into the Enterprise‘s prequel era. The events surrounding the Defiant are specifically referenced in "Despite Yourself," which is a solid outing that sets up this new setting and looks to be just the beginning.