There are a lot of theories surrounding Star Wars: The Force Awakens, and frankly, most of them are pretty out there, crazy, or just pretty dumb. But one of these keeps sticking with me, and it’s because of some very important history in Star Wars, both in today’s current canon and in what is now called the “Legends” stories of the old Expanded Universe.
The theory is that Rey and Kylo Ren are siblings, or even further, are twins. Rey has talked about family in her voiceover, afterall, and we assume from the lines of dialogue said by Kylo’s toys that he’s trying to recruit someone to his side. So why does this stick with me so strongly? Because there’s precedent.
Of course, the first that everyone knows is simply Luke and Leia. One of the greatest lines in Star Wars history, and a personal favorite, is the very simple, “No, there is another.” Yoda says this to Obi-Wan Kenobi, and it’s our first real indication that Leia is not only Luke’s twin, but has the Force on her side, as well. That has since been explored, both explicitly stated in Return of the Jedi, and teased a little less explicitly in the pages of the new canon comic books from Marvel Comics.
But there was also an arc of Star Wars: The Clone Wars, the animated series that’s also all official continuity, that dealt with twins of a sort. In that, the “Mortis Trilogy,” Anakin, Obi-Wan, and Ahsoka wind up on a mysterious planet that floats in out of nowhere called Mortis. It turns out it’s basically the focal point for The Force (think of it as the Rock of Eternity or Vanishing Point, comic book fans). There, the Force is kept in balance by a Father, who wields both Light and Dark Side, and a pair of siblings – Daughter, the light, and Son, the dark. If they're not twins in the strict sense of "siblings born at the same time," then they're certainly twins in the sense of the two sides of one coin. Anakin Skywalker, when referred to as “the chosen one” and how he’s “supposed to bring balance to the Force,” was picked by the Father to replace him.
And he said no.
This helped tip the scales in favor of The Son, and thus the entire galaxy was plunged shortly thereafter into the Dark Times, the era of the Empire at the height of their power. Here’s where we go from fact to theory.
The theory is, because Anakin had been chosen to be the new Father by the Force itself, it didn’t let that go. Indeed, he fathers a set of twins, Luke and Leia. Luke is tempted by, and even arguably goes into the Dark Side, albeit extremely temporarily in Jedi. Leia, meanwhile, remains the hope for the Light, and guides them back into it.
In the Legends universe (again, non-canon now), Leia and Han were married, and they had twins named Jacen and Jaina. As the Force-sensitive one to first have children, Leia became the new figurehead of the Force in that scenario. Sure enough, Jacen fell to the Dark, and it was up to Jaina to stop him.
Now, we know the movies have abandoned the old Expanded Universe, and are said to be telling 100% completely new stories. But while the EU is no longer in any level of canon, the Clone Wars definitely still is. Having an imbalanced Force, especially upon an “awakening” would certainly allow for two new avatars to emerge, and who better than a pair of twins, the son to the Dark and the daughter to the Light?
The biggest problems with the theory are that it might be a bit too much of a retread (sure, Abrams wasn’t around for those Legends stories, but more than one member of the Star Wars Story Group at Lucasfilm definitely was), and that we don’t even know if Han and Leia are married or still together, let alone have any children. Still, it’s an intriguing possibility, and now you have the “historical” context in the universe that makes it one of the more reasonable theories.