Chloe and Rachel needed $3,000 to get out of town. Of course, starting a new life in California is way more expensive, but their desire to leave Arcadia Bay allowed them to believe that they were just $3,000 short of leaving their problems behind. For Rachel, it was about leaving the world around her behind to prove that she doesn't need it at all, so she does not owe them anything. Rachel was out to prove something, but not Chloe.
For Chloe, it was truly about feeling that level of trust and vulnerability she felt when her dad and Max were with her. To Chloe, feeling like that again was her endgame. Unfortunately, this had to create an imbalance in their relationship which would be explored later on. Anyway, as far as Chloe knew, her relationship with Rachel was going perfectly. They were both keen on leaving Arcadia Bay, perhaps as soon as Rachel finishes school.
After a few years of a solid relationship, Rachel suddenly disappeared. Everyone, including her parents, were certain that she just abandoned them. Rachel was trying so hard to prove something to Arcadia Bay, but didn't realise that Chloe will be the only one who will actually look for her if she disappeared. Rachel didn't get to know this before she... left.
Chloe spent the next few months posting missing posters all over Arcadia Bay and devolving into a much worse person. She was getting close to Nathan Prescott, which went from bad to worse. After he drugged and abducted Chloe, Chloe managed to barely escape this situation. She then decided to capitalise on that situation so that she could get the money to leave Arcadia Bay. Most people know this to be the biggest mistake she ever makes. The mentally unstable Nathan Prescott kills her in Blackwell's bathroom.
Now, for those who chose the "sacrifice Chloe" option, this is where her end is. Chloe dies abandoned by Max, fighting a losing battle against the theory that Rachel abandoned her too, never made up with David, never made peace with Joyce, and was killed in the bathroom of the jail she tagged up the last time she was there. She never found Rachel, she never got to leave Arcadia Bay, and she never got to pass on her father's camera to Max.
Well, after being saved by a random fire alarm, Chloe managed to disarm Nathan and run away. Soon afterwards, she got to save Max. This created a really uncomfortable car ride back to Chloe's. Chloe took this time to give Max her own perspective of their relationship. You see, Chloe has lost her ability to empathise thanks to her single-minded hatred of everyone besides Rachel. This is something that will fit into the moment of truth at the end of the game.
Chloe let Max know that as far as she knows, Max and Chloe were great friends, she moved to Seattle, found a better life, and decided never to contact again. Observant folks might have noticed that Max was given IEP during her schooling, and might be facing a social disability. Contacting her best friend whose dad died and balancing her own social life might have been an unobtainable goal for Max. Chloe used this car ride to put Max down.
Chloe also finds out that Max is the one who saved her life. Instead of apologising in a similar manner in which she expected Max to apologise, she allows Max to be forgiven. She is clearly not ready for anyone else to have power over her, even if it is resolved through a simple apology. Chloe, so far, has been characterised as an awful person.
When we reach home, we can see that, if pushed far enough, David WILL slap her. For Max and the entire audience, this is a horrifying scene where we do something Chloe does not: we empathise with her.
Chloe's terrible and self-centred behaviour continues the next day after learning that Max is the closest thing to a God. At the junkyard, we learn that she has been too friendly around Frank the drug dealer, and was held at knife-point. Chloe isn't ready to accept anything in her life as her own fault. Interestingly, this creates a new interesting "Middle Way" dynamic between Max and Chloe.
Max is a pushover and silent in Blackwell, and she is always ready to apologise for everything, Canadian style. She gets bullied by Victoria and accepts it as a part of life. Chloe, on the other hand, rebels. She rebels against Victoria. She even does so against Max, someone who helps her. Both of these characters need to absorb each others' personality to some degree.
Later, in Frank's RV, Chloe finds about Rachel's infidelity to her. This seems to be the breaking point for Chloe. She starts attacking everyone she feels is responsible for her feelings, including her mother, Max, and William... Rachel embodied the trust she had in Max and William, and if even she could betray her, then so can William and Max.
This is where she says the infamous line. "I have to blame someone, otherwise its all my fault." This is actually a surprisingly poignant line for her. She is, at this moment, fully aware that people she is attacking are not after her, but still refuses to come to that moment of full realisation which will allow everyone else more power over her. In fact, she is moving away from that crystalising moment and take the power back from Rachel and Max.
All of this would be a major turning point in a less realised story, but as we find out, it is her anger boiling up that day. The next day, she is calm. She knows that Rachel, despite what she did, does not deserve her fate. She went back to continue her investigation. This investigation leads to, perhaps, the most devestating moment in the game: Chloe finding out that Rachel died after being abducted and overdosed. It feels painful watching Chloe weeping there. She had planned her entire future with Rachel. She got to know Rachel's entire life within a few days, made HER a huge part of her own life, and now, she is simply dead in a brutal way.
At this point, Chloe does not care about any other development. Getting revenge on Nathan Prescott is all she can think about. In a way, her entire life was ended a second time. Again, Chloe was as reckless and unempathising as ever, but this time, it seems impossible to stop her. Chloe, at this moment, is at her most broken, defended and un-developing self, which is why it is funny that she is easily manipulated by Jefferson through her Achilles' Heel.
After a complicated mess in episode 5, this version of Chloe was only tamable by a Max who finally takes a page out of Chloe's book and calls her out. Max here tells Chloe that what she is doing is stupid and selfish and would lead to her death, and that is something Max does not have the strength to face. Despite the subtle nature of the scene, it might as well be one of the most important ones for Chloe. Her entire personality after Rachel's disappearance is put in front of her and she has to confront it. Chloe sees herself as the uncaring and spoilt brat she has been acting as and... apologises to Max. She stops for a moment and let's Max take charge for that duration. Without hesitation, she follows this plan, even though it relied on trusting David. At this point, Chloe has stopped being single-tracked and is ready to see the big picture.
Well, her character arc doesn't come a second too late, since now, her fate is to be decided. However, more interesting than what the player will decide is Chloe accepting her own fate. Her life is weighed against a thousand other, and she is tired of letting herself be at the center of everything. She says that her "step... father" deserves better than having Joyce die in a storm. It is also important to know that this is not Chloe accepting her death, nor is it her forgiving the town for what happened to Rachel.
Before saying that she has to die for this storm to disappear, Chloe cries one final time. Death is not something that someone can simply accept, and that goes so much more for a young girl who saw everyone around her leave her or die. Chloe knows that she can never get her life with Rachel, but she needed a moment to actually care about other people.
Max can let the town be destroyed, the follow-up to which is received in a few comics published years later and is still ongoing. As for the other ending, it has been discussed.