One of the greatest Star Wars head-scratchers in the new trilogy is the connection between Kylo Ren and Rey. Are they brother and sister? Ill-fated lovers with weird sexual tension? Really, what's the deal with Reylo? The Last Jedi offered the answer of Supreme Leader Snoke linking these two, but The Rise of Skywalker further serves up the idea of a "Force dyad" to gesture at a grander theme of balance.
Before diving into this concept, let's break down the jaw-dropping reveal in The Rise of Skywalker. Episode IX brings back Palpatine, who used Snoke, Kylo Ren's former master, as a puppet. Rey, it turns out, has Sith blood coursing through her veins; she's none other than Palpatine's granddaughter, as opposed to a nobody per Kylo Ren's previous claim in The Last Jedi.
Despite coming from a dark lineage, Rey gravitates toward the light side. Ben Solo is somewhat the opposite of Rey — a Skywalker who goes from the light to the dark side of the Force. The Force needs a balance of the light and dark sides, which is why it connects Rey and Kylo (respectively Sith and Jedi descendants), allowing them to do things like see visions of each other. Kylo explains that this balance is a "Force dyad," that they're "two that are one." He wants to wield this power with Rey to seize the throne from Palpatine.
Their Force dyad seemingly goes beyond Snoke orchestrating a relationship between them in Episode VIII. Palpatine momentarily uses their Force dyad to restore himself, calling it "a power like life itself." But a reclaimed Ben and Rey exercise this balance to take down the evil Emperor. Their connection wasn't meant to last forever, though. Ben sacrifices himself to resurrect Rey after the showdown with her grandfather, sharing one bittersweet kiss with her before his end. (Sorry, Reylo shippers.)
Director J.J. Abrams has long been fascinated by this symmetry between Kylo and Rey. In an interview with Vanity Fair, he said that the characters are "connected in this profound way, drawn to each other, curious about each other, knowledgeable about each other." Abrams added, "They also are, by definition, working on opposite sides of things. And so the dichotomy of those characters is the thing that, for me, is most fascinating."