The thing is that the Predator could be training the protagonist to be a hunter which might not be out of the question for them. We have seen them outfit Humans in the comics and tie-in material for Predators. Even Noland was able to use Predator equipment and the Predator killer can be used by Humans even if it's seemingly meant to be used by a Predator. There definitely is some overlap to who can use the technology and skills is what I'm getting at. And given the talk about the Predator 2 pistol it might be that the Predator perceives our hero as a hunting dog. Basically a tool to get what it wants which could lead to the final battle. Less of a fight to the death and more showing her master that she is not a tool, she's as much an equal as it is (y'know, relative to a 500 pound space serial killer).
And that would line up with what we know the protagonists deal to be. She wants to be one of the bois. Nobody will let her and while she gets what she wants out of the dynamic with the Predator, she isn't his equal until she can best him which is what she wants. The Predator obviously wouldn't give two shits and a f**k about who she is so long as she's useful which means the Predator would be filling the role of both Kratos and the final boss.
While I am against a team-up, I don't think its another sled ride of friendship, it's probably more akin to the 2010 classic Predator.