Rachel is a time traveler - a fan theory
I have a theory that Rachel has time travel powers (and I believe it was already stated that she would have some power). Things obviously took a turn for the worst and maybe she decided to go back in time and fix her mistakes. It’s extremely clear that Rachel has a thing for Chloe and cares for her. She also acts with a confident and attitude beyond her years not exactly fit for just a 15-year-old, but closer to 19.
I think Rachel not only already knows Chloe, but knows everything about her. Which would explain why she knows too much that she shouldn’t and couldn’t about Chloe, so early on. They were best friends in the LiS timeline, maybe even were friends with benefits from time to time, but maybe Rachel was always afraid to confront the relationship and the fact that she is into girls.
Being gay is not an easy thing for the post popular girl in school, especially for one that’s so drop dead gorgeous like Rachel. So maybe she always had feelings for Chloe but never consummated them, never was able to bring herself to act on them. Maybe it was too late. In the BtS timeline, maybe it shows what would happen if Rachel got time travel powers and decided to go back in time, before she was murdered, and make things right. A proof of this is the fact that Frank said Chloe was part of the problem, and that he was jealous. Maybe her and Chloe got closer and closer but then it became too late for her to fix things.
Maybe, like Max, when in Jefferson’s lair and about to die, he dropped some of her old photographs, including the selfie she took at the Firewalk concert - the first time she met Chloe. Or maybe it was another picture, and she went back little by little, as she tested how her powers worked. Maybe that’s when she originally got her time travel powers - just before death, in a moment of ultimate crisis - I can’t be sure.
Rachel’s reactions to Chloe in BtS strike me as sincere and original, like it’s the first time she hears some of the things from Chloe. Most importantly, I think Rachel is genuinely pleasantly surprised at how hard and fast she is falling for her best friend, when she decides to do things right, and she decides to be as assertive as humanly possible to get her girl.
But I will finish my rant with this:
Rachel calculated things so carefully so that Chloe would open up to her (a possibility to indicate that maybe in the LiS timeline Chloe had never told Rachel how she fully felt either, afraid, and in her own words “Didn’t want to push, in case…” in case she was straight. It seemed in LiS more like Chloe was following Rachel around like a puppy. I think that’s also a reason why Rachel is so terrified in the junkyard scene because it’s too early in their relationship for her to ruin the seduction and let Chloe sees how she cries, and she knew she would. Maybe in this new timeline Rachel found out about her dad having an affair with Sera. Maybe the reason she’s so upset at her dad isn’t only that he cheated, but because she knew he abandoned her in the time she most needed him and he didn’t even try looking for her during the 6 months she went missing. Maybe he even knew she was dead, because of all the shady business Sera was in, causing all sorts of trouble. How would Rachel know that? Another theory for another day.
Rachel has the same time travel powers as Max. I think Rachel went back
in time to try to fix her mistakes and to get with Chloe, who she
obviously had to always be attracted to. What she maybe hadn’t expected
was to fall for her so fast and hard, and to realize that this was truly
the love of her life. So, she did it all for love. To me, this is
beautiful beyond words.
In this scene, the moment when Rachel breaks away from the kiss, she has a look of surprise that says “Wow, she’s the one. I did things right.”