The following is a spoiler for the Netflix series The Sandman.
The Sandman, a second half of Netflix's The Sandman, is adapting The Dolls House, a comic book epic written by Neil Gaiman. In this story, Dream of the Endless (Tom Sturridge) must track down escaped Nightmares and Dreams while dealing with Rose Walker (Vanesu Samunyai), a dream vortex that threatens to wipe out the waking world.
What Is a Dream Vortex?
When we close our eyes to sleep, we enter the Dreaming, the kingdom Morpheus controls. However, we do not enter the whole realm; instead, we only have access to an individual and fragmented version of the Dreaming. If the barriers between dreams are broken, all sleepers find themselves in the same place. Furthermore, the process of joining dreams also destroys the Dreaming itself, as its many inhabitants and locations collapse together, destroying all life on the planet in a blink.
A dream vortex is a living organism that has a special connection with the Dreaming and is capable of navigating through other peoples' dreams. What makes the dream vortex so dangerous is that it can also break the walls between dimensions. To make matters worse, the dream vortex cannot control its own powers and will eventually destroy the world even if they do not intend to. Thats why Morpheus is charged with dismantling any dream vortex, the only occasion when the King of Dreams has the right to murder
No one knows why a dream vortex appears and where they originate. Fortunately, they are extremely rare, only appearing once every age. So now Dream of the Endless is willing to do whatever it takes to destroy dream vortexes, even when they are lovely people like Rose.
Rose Walkers Family History
Rose was not intended to be the dream vortex of this age; it was Unity Kincaid (Sandra James-Young), her great-grandmother. However, when Dream became captured by Roderick Burgess (Charles Dance), Unity fell into a deep sleep. Unity slept until Dream escaped his prison, losing her whole life in the process. The abilities of the dream vortex passed down until Rose was discovered more than a century later.
Unity is awake when she encounters a handsome man with golden eyes in her dreams. The man is actually Desire, Dreams' sibling, who knew that the woman's descendants would eventually become a dream vortex.
The Endless are quite adept at killing humans that aren't threats to their kingdoms. They are prohibited from spitting their families' blood. Desire ensured that the following dream vortex would have Endless blood. So, when Dream would slay the dream vortex, he'd be exposing himself to harming others.
Unity sacrifices her own life to save Rose, taking the place of her great-granddaughter as the dream vortex during Season 1's finale. Rose has now recovered all powers related to the dream vortex.
Rose is also part of other comic book narratives, so if Netflix wants to continue adapting Gaiman's work, they'll need to bring her back sometime. Rose is also a descendant of Desire, so a possible Season 2 could utilize the character to probe the tensions between the Endless family members.