"Godspeed," episode 18 of The Flash season 5, has finally given Nora West-Allen (aka XS) a proper origin story. While the show has slowly revealed details on the life of Barry Allen's super-speedster daughter over the course of season 5, Nora had never been given a full episode devoted exclusively to her until now.
Nora first revealed herself to Team Flash in the season 4 finale, "We Are The Flash." However, viewers got to see Nora several times throughout the course of season 4, as she spied on Team Flash and arranged a series of accidental meetings, including disguising herself as a waiter so that she could see her parents' wedding and talk to the father she never knew for a few minutes. The season 5 premiere "Nora" revealed how Nora had come back in time to see her father and wound up intervening in his final battle with The Thinker, altering the timeline as she knew it. However, it was not until season 5, episode 18, "Godspeed" that the audience got to see Nora's life in the not-too-distant future of Central City 2049.
The episode gives context to what few details we knew about Nora's life in her own time. We see Nora in her day job as a CSI with the Central City Police Department - a job she took in an effort to emulate her father. We also learn how Nora discovered the microchip implant that negated her powers - an action Iris West-Allen took to prevent her daughter from further following in her heroic husband's footsteps. Beyond establishing this continuity, "Godspeed" also gives a greater insight into Nora's character, revealing how she was spurred to become a hero even before she found out she was the daughter of The Flash, thanks to her best friend being murdered by the episode's titular villain, Godspeed.
It is worth noting that "Godspeed" is full of Easter eggs and nods to earlier episodes of The Flash, further drawing parallels between Nora and her father, particularly referencing back to the show's pilot episode. Both episodes open with Barry and Nora being late for work, and fighting their way against a crowd to get to a crime scene. Both lose control of their speed the first time they use their powers and make a crash landing into the back of a laundry truck. (Barry's was for Gambi Cleaners. Nora's was for Gambi & Sons.) These tributes extend beyond the pilot episode of The Flash, with Eobard Thawne instructing Nora on how to use her powers to phase through a concrete wall using virtually the same words he did when he taught Barry the same trick in "Tricksters," episode 17 of The Flash season 1.
Ironically, as this episode shows how Nora-West Allen is every inch Barry Allen's daughter, the episode ends on a heart-breaking note where she's seemingly rejected by the father she longed to impress. Left unable to trust Nora in the face of the revelation that she was trained by his archenemy, the Reverse Flash, Barry abandons Nora in the future and tells her never to travel in time again. This moment is all the more painful, coming after we see, in flashback, what prompted Nora to try and return to the past in the first place - a video message her father left for her, just before his disappearance, saying that he would always love her no matter what.