'The Sandman': Desire's Plan To Kill Dream Using Rose Walker Explained
In the Netflix's series we never get an explicit explanation as to what exactly Desire has been planning to achieve by making Dream kill his kin.
In the series finale we learn that the whole plan was set in motion by Desire, who, by violating Unity Kinkaid while she was sleeping under the curse of "sleepy sickness", has created a dream vortex. Not just any vortex: knowing that it was actually Unity who was destined to become a dream vortex, have it not been for the sleepy sickness, Desire fathered her child, Rose Walker 's biological mother. The power of a dream vortex was passed from Unity, unable to fulfill her destiny due to the sleepy sickness, to her granddaughter Rose.
That's how in the series finale Unity was able to stop the catastrophe by getting the vortex powers back and sacrificing herself so that Rose could live her life.
When Rose became a dream vortex, she was related to Desire and their siblings, Dream included, by blood. Thus, knowing full well that Dream will have to kill Rose, as all dream vortexes must be killed, Desire essentially lured Dream into killing his kin.
That much is shown in 'The Sandman's finale, but it's only half of the actual plan. In the comics, Desire's ulterior motives and schemes explained much more comprehensively than in the Netflix series.
You see, by spilling, however unknowingly, the blood of his kin, Dream becomes a prey to the Kindly Ones, who in the original comic series run him down and eventually kill him. That's why Desire says in the Netflix series that it's Rose Walker who is going to become Dream's undoing.
Fun fact: in the comics Rose Walker actually gets to know her "maker". In issue 65 Rose meets Desire in her sleep, learning that she's Desire's granddaughter. Needless to say, Rose was not impressed.
In the comics the love/hate relationship between Desire and Dream is well established; their backstory is quite tragic, seeing how they were very close in the past, and Desire was originally Dream's favorite sibling. However, in the Netflix adaptation we only got a glimpse of Desire's animosity towards Dream without any explanation as to why they actually want their sibling dead. Hopefully, this side of 'The Sandman's canon is going to be explored more in Season 2. However, as of this moment, there's no news of the series being renewed for the second installment.