This blog contains spoilers from “Nimue” — Season 5: Episode 7 of “Once Upon A Time”
We learned the identity and backstory of the very first Dark One — Nimue. Meanwhile, the rest of the heroes continued to try to reclaim Excalibur.
The episode begins with a flashback “1000 years before the age of Arthur” as Merlin and another man are stranded in a desert and find the Holy Grail. Merlin is able to drink from the grail and attains immortality. After gaining these powers, Merlin uses them for good for hundreds of years, healing people, until he meets a woman (Nimue) whose village is burned to the ground by a masked man.
As Once Upon A Time has taught us, all magic comes with a price, which Merlin has learned in the most painful way — seeing everyone he loves die one after the other while he continues to stay young. He decides he doesn’t want to live forever without Nimue, so the two go on a quest to turn the Grail into a sword so they can live their lives together.
But, just as the sword is forged, the masked man reappears and stabs Nimue. Although, unknown to Merlin, she had drank from the Grail, she pops back up, grabs his heart and exacts her vengeance for her village. The decision to kill blackens Nimue’s heart and turns her into the first Dark One.
Back in the Camelot, Merlin asks Regina and the others to recover the piece of Excalibur from Arthur while he and Emma go in search of an ember of the fire of Prometheus to forge it back together.
Merlin brings Emma to the site of Nimue’s fateful encounter to summon her since she is now the keeper of the ember. After resisting the darkness and the urge from Nimue to kill Merlin, Emma takes the ember and heads back to Camelot with Merlin until he mysteriously vanishes.
Zelena had helped Regina, Robin, Hook and Charming sneak into Arthur’s castle to steal Excalibur. When they make it to the Round Table, Zelena emerges with a kidnapped Snow, frees Arthur and helps him tether Merlin to Excalibur, allowing it to become like the Dark One dagger.
As the episode closes, we return to present-day Storybrooke, where Dark Emma retrieves the ember she took from Nimue and uses it to re-forge the sword in her basement while the spirits of all past Dark Ones look on. Ignoring Merlin’s warning years earlier to leave Excalibur alone, she reaches forward and is ready to wield its power.