Spoilers for Star Wars: The Last Jedi ahead. In the newest Star Wars film, our hero Rey thinks that Luke Skywalker will bring her answers, and she isn't completely wrong. She does get some mysteries solved, but there's still a lot we don't know. Most fan speculation seems to be incorrect with regards to this mysterious girl, but that said, these Episode 9 theories about Leia and Rey show that their relationship doesn't need to end after The Last Jedi, and there might be much more to be explored. The two women share a deep, undeniable connection.
In The Last Jedi, Kylo Ren tells Rey that her parents were nobodies who sold her for extra cash and later died equally inconsequential deaths. The theory about her being a Skywalker descendent is also seemingly dashed by Supreme Leader Snoke, who claims to fabricate the Force link between Rey and Ben. And it's possible that Rey's parents really are nobodies; at the end of the film, the force-sensitive child finding inspiration in the tales of Luke Skywalker (just like Rey did on Jakku) might solidify the concept that there will always be heroes and chosen ones across the galaxy, regardless of who their parents are.
But like, here's the thing. Why, then, did Luke's blue lightsaber call to Rey in the first place, showing her both Luke's memories and her own? Why did Obi-Wan, in the same vision, speak to her and call her by name? Why do Leia and Rey share meaningful stares at the end of both The Force Awakens and The Last Jedi? Snoke couldn't have manufactured that. There is at least a strong possibility that Leia and Rey are connected in some meaningful way.
There's also the fact that Episode IX was meant to be Leia's story, as well as he fact that The Force Awakens gave Han Solo some closure, while The Last Jedi focused on Luke. Since Rey is undoubtably the hero of this trilogy, it's possible that whatever her connection to Leia is, it was supposed to be central to that final act. Here are some theories about how that'd happen.
They're Mother & Daughter
It'd be such a bummer if Han and Leia's only child was Kylo Ren. If fans want to hold on to Rey being part of this big unhappy space family, the most obvious answer is that she's Kylo's sister. The two of them certainly looked like the Wonder Twins when they were battling Snoke's blood red lackies. Rey could also be Leia's daughter from a different dude, not Han, and be half-siblings with Kylo.
They're Aunt & Niece
Again, if we assume that Kylo Ren was lying, the theory that Rey is Luke Skywalker's daughter still stands. You'd think he would have said something — but maybe that's why Kylo thought Rey would turn to the dark side if she learned the truth about her parents. It might make her angry, and as we know, anger leads to hate, and hate leads to suffering.
She's Her Only Hope
If instead Rey is a Kenobi, she's connected to Leia in that she represents hope. RD-D2 may not have played Luke the original Leia hologram as a cheap ploy to get him to come with them. It could have been a clue that the girl is related to the Jedi Master most connected to the fated Skywalkers. There's a certain poetry in that, at least.
Leia Knew Her Parents
We presume, when Ben (the baddie known as Kylo Ren) tells Rey she was sold by her junk trader parents, that the person who bought her was Unkar Plutt, her ultimate boss on Jakku. However, what if her parents sold her to a higher bidder? What if she was sold to The First Order, or even the resistance itself?
One of the most interesting aspects of The Last Jedi is how our heroes learn that even the good guys do bad things. Poe is disillusioned by the strategies of the resistance. Benicio Del Toro's character DJ teaches Finn and Rose that there are weapons dealers who benefit from both sides as well.
It's entirely possible that Rey's parents are nobodies but Leia still knew her, and arranged for her to be sent back to Jakku for safety.
It's Just A Feeling
In a way, Rey is what Leia would be like if she grew up like Luke — though even Rey didn't have the benefit of Uncle Owen and Aunt Beru's love and roof to sleep under. Maybe Leia simply sees herself in this girl.
With or without a significant heritage, Rey is a phenomenal character who stands alone. Both women are. Maybe Episode IX will reveal more about the two of them, but no matter what, Star Wars is better off for them.