A case for OG-verse Weskada
The way that Ada talks to Wesker in Separate Ways is very different from how she talks to literally anyone else in the series. She is more casual/colloquial with him than she is with anyone -- with the sole exception to this being the way she talks to Leon in Damnation. Basically, the way that Ada talks to Leon in Damnation? Is how she talks to Wesker in Separate Ways.
And... what happened between Leon and Ada leading into Damnation?
Just saying.
Separate Ways tried to heavyhandedly put more sass into Ada's character in general, but it's more honest when it comes to Wesker. She cracks jokes at him and emotes openly at him. She gets openly annoyed with him at times, and even has a tone of "dude, come on" with him when he gives her a ridiculous order.
She just always seemed very... comfortable with him.
And it always struck me as weird that Wesker wanted Leon dead so badly in Separate Ways. It is the only time in all of Resident Evil that Ada is given orders to assassinate/kill someone. And it's the way he goes about telling Ada to kill him:
"And that US government lapdog, Leon -- if you do happen to encounter him, put him out of commission. We can't let him interfere with our plans. [...] He's a survivor of Raccoon City. We could do without the extra distraction. Take him out."
Like, obviously, Wesker sees Leon as a threat to Ada's mission, and the pretense that he gives overtly for it is "If he can survive Raccoon City, there's no knowing what he's actually capable of."
But the "extra distraction" part always seemed like a weird choice of words. It was like Wesker knew that Ada had some sort of attachment to Leon already and thought that he would get in the way of her mission not because he'd overpower/kill her, but because she'd be too distracted by him to do her job.
And that struck me as being a little jealous.
Later, when Ada reports to Wesker that Luis is dead and Saddler has the Sample, his response isn't... anger or frustration or irritation or even disappointment. It's:
"Have you had a chance to eliminate Leon?"
It's only after Ada says no that Wesker gets the idea in his head to use him. He didn't ask her that with the intention/plan of using Leon if he was still alive; he just wanted to hear that he was dead -- and, when he didn't get that, he drums his fingers against the arm of his chair in thought and then comes up with the idea to use him.
And what's crazy about it is that Leon plays his part perfectly and unknowingly does exactly what Wesker wanted him to do -- and Wesker still wants him dead. And since he's clearly not going to get his way and have Ada do it, that's when he decides to sic Krauser on him.
And after Krauser dies, Wesker is still on this, and he's all like: (paraphrased) "Make Leon and Saddler fight each other and then kill the winner. MAKE SURE YOU KILL HIM, ADA."
And then he fucking hangs up on her.
It's starting to feel a little personal, at this point.
And then Umbrella Chronicles happened. And it's revealed that Wesker saw all that shit go down between Leon and Ada in real-time.
Which now makes his desire to see Leon dead feel really, really personal.
When Wesker contacts Ada in Umbrella Chronicles, he does so via video chat (somehow in 1998 the tech for that existed shut up), and her reaction on seeing him fucking shocked me.
I expected that her reaction/tone would have a hint of "oh shit" behind it or "oh god here we go" or even just cold, unfeeling business -- kind of like how a soldier "Sir"s their CO. But that's not what she does.
She sighs his name in that dreamy sort of way she sighs Leon's name during Separate Ways.
At the very end of Umbrella Chronicles, Ada says in her narration:
"[Wesker and I] are both used to being backstabbed and manipulated. I have a feeling our relationship will last for a little while longer."
Ada's hookshot? That has become a huge staple of her gameplay and character design? It was a gift from Wesker -- it's what he gave her so that she could make it out of Raccoon City alive.
And she never stopped using it.
NOW, WITH ALL THIS BEING SAID
I am not trying to make a case that Wesker and Ada loved each other or that their relationship was romantic at all.
What I am saying is that I do think that their relationship went deeper than just a professional working one. I think that they were definitely sleeping together, and I think that Wesker knew and understood who Ada was better than anyone ever has in her life, and I think Ada knew that.
Wesker is a sociopath, but he still trusted Ada's ability and her judgement and seemed to, on some level, also genuinely enjoy her company.
And Ada, I think, found some comfort in Wesker's familiarity and felt a connection with him based on their similar past experiences. I think that her keeping the hookshot even after she betrayed him and after he'd been killed is her way of honoring who he was to her and what he did for her without remaining beholden to him in any way.
Leon was the reason why Ada ultimately betrayed Wesker in the end, but it wasn't a matter of "Well, I love him now, so I'm going with him. Boy, bye." Ada says in Umbrella Chronicles that her meeting with Leon changed her, and she says at the start of Separate Ways that betraying Wesker is part of her own objective -- which, presumably, has to do with the way Leon changed her. It had to do with a change in worldview, not a change of heart.
And I think that what Remake is trying to do is to show that change in her happen in real-time. That's why she doesn't go into RE4make already intending to betray Wesker; it's a decision she comes to organically as a result of Leon's impact on her inspiring her to ask questions as to where her efforts are going.
She didn't betray Wesker because she fell in love with Leon. She betrayed Wesker because she started to look at the world differently and realized that Wesker's ambitions were incompatible with her new worldview. It wasn't personal -- it was just that their lives were now going in two different directions (two separate ways, you might say ayyyyyyy).
But I think that there will always be a part of Ada that's grateful to Wesker and holds some degree of affection for him -- even if it's not at the intensity of actual love, it was still meaningful, and he still had a profound impact on her life.
In some ways, I view Ada's attachment to Wesker the same way that I view Leon's attachment to Ada in the OG timeline. It's not true love, but it was something that kept her bound to him and that she found comfort in when she felt like she had nothing else and her life was spiraling out of control.
Ada is a part of Leon that he thinks he can't let go.
And I think that Wesker is a part of Ada that she thought she couldn't let go, until she finally did.