Do you ever think about how fucking weird it must have been for Duke after Heather's death?
Like, yeah, she wanted Chandler dead, but she's also been listening to Heather's orders for who knows how many years while being physically incapable of disobeying them or standing up for herself. Even if she wanted Chand gone, suddenly just not having anyone to tell her what to do must have been really jarring. Like, she suddenly has a free will entirely of her own, with literally no one that's capable of saying something and causing her to just follow out of instinct. She probably spent half the time internally waiting for an order that never came while she was copying Heather's personality. She was probably waiting for Heather's voice to call out telling her to shut up again whenever she spoke. Not out of missing her exactly, but just out of not being used to doing whatever she wants whenever she wants without anyone around to tell her anything or scold her for it. Even if she hated Chandler, as she obviously did in one way or another, she was probably always half-waiting for her to just appear again and for everything to go back to how it was, because if someone spends that long listening to every order that comes out of someone else's mouth, you end up attached whether you hate them or not, and so if that just suddenly disappears, it'll feel wrong.
idk there's just no way in my mind that Chandler could physically control Duke's digestion and physical movements, and then Duke could just be totally okay with her being gone. Could just not even kind of miss her, whether she wants to miss her or not. The Heathers were all close in one way or another, whether they wanted to be or not. McNamara is deeply co-dependent towards both of them. Chandler can physically control Duke's autonomy. Duke has a burning hatred for Chandler. Duke is deeply jealous of how Mac is treated better than her. Duke wouldn't be jealous that Mac was treated better if she didn't care about Chandler's opinion of her at least a little bit. Chandler wouldn't let Mac put her arm around her if she didn't at least subconsciously care about her/feel comfortable around her. They were all close in some way, even if it was subtle. It's a toxic, co-dependent relationship, and even if it ended when Chandler died, you can't just leave something like that and be totally fine. You can't just leave and not feel uncomfortable about it not happening anymore.
If you're in a relationship like that and it just suddenly stops, no matter how relieved you are to be rid of it, you'll end up lost. Even if you hated the person who disappeared, a small part of you would miss them, would be waiting for them to just come back and for the cycle to continue. As much as Duke becoming power-crazy was because of her repressed anger, in my eyes, she practically took Chandler's personality as a coping mechanism, there was no Chandler to boss her around, so the only option she saw was to become Chandler, because she was lost without her. Duke could've just been glad that Chandler was gone, she could've just become the leader as she was, but she began exactly copying the other Heather, and then pushing further than Chandler ever went with how power-hungry she is due to repressed anger.
Basically, if Veronica had made the three get couples therapy (and therefore if it wasn't 1989) before Chandler died, Duke would've never become a power-hungry maniac, and therefore Mac wouldn't have almost killed herself, because there wouldn't be all this pent-up anger mixed with kind of missing Chandler that Duke obviously didn't know how to deal with, because she was never allowed to deal with it. They would've been fine if they all had just been a little bit more open about how gay they were. And even if you don't ship them, they were still technically friends, so no matter what, Duke would find herself a bit lost without Chandler to tell her what to do, even if she hated Chandler telling her what to do, and nothing could fix that.
