Spoiler warning: Spoilers for Season 1’s main story; no later-season or later-comic outcomes.
Unity takes the vortex from Rose and dies, allowing Rose to live without Dream killing her. The Sandman’s first season resolves that immediate threat while revealing that Desire had placed family ties inside the danger.
Why can Unity take the vortex?
She was originally meant to carry it, but Dream’s imprisonment and her long sleep displaced its manifestation into a later generation. Rose gives the power back to her great-grandmother.
The transfer provides another answer to a duty Dream has treated as unavoidable. Rose does not have to die merely because she is the person in whom the threat currently appears.
That distinction gives Unity agency at the close of a life shaped by forces she did not choose. She becomes part of the solution rather than only background explaining Rose’s ancestry.
What was Desire trying to achieve?
Desire is the golden-eyed parent behind Unity’s pregnancy, making Rose part of the Endless’s family. Destroying her would therefore make Dream responsible for killing his own kin.
The family connection changes the apparent simplicity of his duty. A threat to the Dreaming has also been arranged as a trap for the ruler required to deal with it.
Understanding that intention matters more here than importing later consequences from the comics. This explanation stops at the first season’s disclosures.
Has Dream changed by the end?
His decision to let Gault become a dream acknowledges that a being need not remain confined to its original function. That is a smaller but revealing counterpart to accepting another solution for Rose.
Lucifer, meanwhile, prepares a response to Dream’s earlier victory. The final threat does not show a completed invasion or all the events that later source material might suggest.
The season closes with Dream back in authority, but authority is no longer the whole answer. Saving Rose and recognizing Gault require him to revise judgments he initially regarded as fixed. His enemies remain active while the possibility of change has entered his own rule.
Sources: official ending breakdown.