Audience members are first introduced to the Deathless Mother in Season 2 Episode 2 titled, "Kaer Morhen." She appears as a cloaked figure in the dreams of Yennefer, Fringilla, and Francesca, leading them to a hut in the forest with no doors. To see the Deathless Mother of your own will, you must also utter a frightening incantation: "Behold the mother of forests, the Deathless Mother, nesting in dreams. Turn your back to the forest, hut, hut. Turn your front to me, hut, hut."
Fringilla's immediate thought that the Deathless Mother is an evil witch rather than an old Elven god seems to be foreshadowing. One by one, each character is drawn into the hut, and the Deathless Mother describes what each character wants most in the world, offering them bargains in exchange. Yennefer wants her power back, but she initially refuses the Deathless Mother's offer. The Deathless Mother gets frustrated and antagonizes Yennefer telepathically.
During Episode 5, "Turn Your Back," Yennefer faces execution for her witchcraft and escapes by calling on the Deathless Mother at last. The witch appears in her true form before morphing into Ciri, who tells Yennefer, "I'm the key to you getting your power back. And a great deal more than that. All you have to do is deliver me to the right lock. A shattered back door just outside Cintra. Find me. Steal me."
Ciri has been the primary target of The Witcher for her status as the Princess of Cintra and her powers. During Season 2, it's established there are quite a few of her enemies who have been waiting for Ciri to return to her homeland and steal her away, so the Deathless Mother's attempts to manipulate Yennefer into handing Ciri over bodes very ill.
However, Yennefer is unable to give Ciri over, realizing how much she means to Geralt. Instead, the Deathless Mother, who is actually a demon named Voleth Meir, can escape her earthly binding without needing Ciri. She then possesses Ciri, and Geralt and Yennefer must battle hoards of monsters to try and wrench the demon from Ciri's body.
In a last-ditch effort, Yennefer offers herself for possession instead of Ciri, and the demon briefly flees to Yennefer. Ciri teleports herself, Geralt, and Yennefer (with Voleth Meir inside her) to Voleth's homeworld, where Voleth releases Yennefer's body and joins up with the Wild Hunt. The season ends with Yennefer, Geralt, and Ciri together, safe from the demon's influence.
The Witcher Seasons 1 and 2 are now on Netflix.
