Ok so I see a lot of people who don't understand the point of ellabs (EllieXAbby) and I want to attempt to explain why because why not.
The thing is, they don’t know each other.
By the time they interact in any part II post canon fic, it’s their first real interaction after deciding to change. Granted, Abby had already begun changing earlier (she’s the one who refused to initiate a fight after the Rattlers and let Ellie and Dina live at the theatre), but by the time they stop fighting in the Pacific ocean, Ellie has now also chosen to change (give up revenge, which has given her nothing in return so far and doesn't make her feel better. Abby already knows that, because she killed Joel a while ago and has already realized revenge doesn't help).
So now, they’re effectively new people, trying on new skins and personalities while standing beside someone who has seen them at their absolute lowest (Abby torturing and killing Joel is Ellie and Abby's first interaction. And then in Seattle, Ellie picks off all of Abby's friends but that's the first time Abby really sees who Ellie is as a person.)
The level of vulnerability here is insane : fear of judgment, fear of being seen as fake, fear that the new versions of themselves might still be awful and that the other might call them out on their bullshit or worse, expose them. They’re both projecting who they want to be now onto Lev because he’s the only unbiased person left. He’s a child, but he also doesn’t know their complicated past. He's also someone Abby already connected with (she's been with him for over a year now and they likely have developed a strong friendship, meanwhile Ellie raised JJ who I'm pretty sure is a huge reason why Ellie didn't fully spiral upon returning: he gave her something to do and look out for).
And so Ellie and Abby perceive each other through two conflicting lenses simultaneously: the monster the other knows me to be vs. the person I’m trying to become now.
And that’s why Ellabs is such an interesting ship to explore.
It’s about the reinvention of self and the deconstruction of old beliefs in the presence of someone deeply traumatized by those very beliefs.
We know Abby and Ellie’s character archetypes. We’ve seen gruff Joel slowly break through Ellie’s walls (and vice versa), so we’re subconsciously aware that, under different circumstances, Ellie and Abby would likely get along, since Abby is also a version of Joel (as we have seen through basically 95% of Abby's actions, Joel's murder notwithstanding).
We know this shift is possible because we've literally just seen it happen: Abby abandoned her loyalty to the WLF to help the Seraphite kids, despite owing Isaac everything (Isaac gave her a team and resources to go achieve her unique goal of murdering a guy, which was all Abby cared about). We also know Ellie is now utterly alone (Dina broke up with her, there's not returning to the farm to find a happy family. Dina tells her she's not doing this again, which is actually funny because it's also what Abby says at the beach. Ellie's quest for revenge lasts longer than everyone else's in the game. She is the LAST one to change), desperate for either death or something new to care about. She’d never bend for Abby, but Lev--an innocent kid who showed her mercy (stopping Abby from killing her and Dina in the theater)--could make her stick around. He’s untainted. She also feels gratitude; without Lev, she and Dina would be dead.
This also means Ellie realizes Abby has changed. The woman who brutalized Joel with a golf club (yet spared her and Tommy) is now restrained by Lev’s influence (re: theatre scene, where he stops her from killing Dina by calling out her name). Ellie knows Abby is not as ruthless as the act of killing Joel made her seem: Lev’s stayed with her for over a year, and Abby clearly cares for him deeply. This likely also sends Ellie back to her failure as a "mom". Abby stuck with Lev, who's a kid and therefore a "burden", when Ellie hurt Dina when she confessed in the theatre, AND THEN LEFT THEM. I think unconsciously this is a big blow to Ellie who can't help be see the ways Abby did "better" than her.
Also, Abby knows Ellie isn’t a heartless monster. Yes, Ellie murdered all of her friends, but she also confessed and basically sacrificed herself to save Tommy, which is proof she operates by a code. Militia logic dictates that codes matter. Yet Ellie’s violence also shows she’ll slaughter those outside her tribe without hesitation (Abby and surrounding people are not her tribe by that point).
Abby also witnesses what she thinks is Ellie’s mercy when Ellie cuts her down to save Lev. That's why she says "there are boats". She’s offering an olive branch after (mis)realizing Ellie extended one first.
Then again, I don’t think Ellie waited for Abby to set Lev on the boat to act. She followed because she had no idea what to do next. She traveled for months to avenge Joel, only to confront the reality that Abby isn’t the immoral monster she imagined--just a human who suffers like everyone else. Seeing her so emaciated is catapulting Abby out of monster realm and into human one in Ellie’s mind.
And Ellie, as we know, is not a psychopath; her violence isn’t for fun. She’s shaken by Abby’s state and only realizes last-minute (she turns her back on Abby, she looks pensive, she could let Abby go) that sparing her means all of this was for nothing--the one thing Ellie can’t accept. She desperately wants all of this to have been for something. Joel butchered dozens of people to save her. Then Abby tracked and killed him. Then Ellie killed Abby's friends and had to confront her own violence, then her own selfishness by going after Abby instead of staying with her family. If she lets Abby go, then this will have been for nothing.
And now they are stuck together, having gone through all these changes and completely unmoored by the other's action, and then saved by them.
That’s why forced post-canon proximity is so compelling: you take two people bound by hatred and explore how long it takes for their biases to crumble. It's about showing a person who knows you a certain way you aren't that way anymore. They could do this with anyone else, but it would be less interesting, because one of the major appeal of the ship is the forgiveness aspect. Both of each other and of themselves. They cannot do that part without the other.
That’s the interesting part.
Finding meaning after losing everything.
So I wrote a fic about it