OK. SO- Imagine if Neha and Duncan were exes from before Island.
They "broke up" some months before TDI thanks to Duncan's fear of commitment, in which he just stopped talking to her or going out of his way to see her altogether. Basically cut every type of communication between them.
They were good for eachother, (i love them as a duo, and i feel like the complement eachother very well; one can destroy you with words, and the other with his fists) but thanks to Duncan's background and his need to act like a douchebag they didn't really end in good terms.
I feel like Neha thought something like that could happen, and since she already would've made peace with that thought, its not the fact that they broke up what she's mad about, but the fact that he wasn't even able to talk it out with her, or trust her enough to admit his fears and ask for help.
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Then TDI starts, Neha is disguised as Noah, and their whole "piercing" meeting happens. She couldn't believe that he was actually participating in the show, and Duncan was a bit creeped out since the similarities between the nerd and his ex were uncanny. (Didn't take too long after that to discover they were, actually the same person)
So Neha ends up getting booted 3rd not only because she thought weeks in a 5 star hotel were better than international humilliation, but because she got tired of faking she didn't know who he was and all their history. (The glares he got were 100% real) ALSO the fact that she had to witness him flirting with Courtney.
-Her gender does get revealed at the end of the season-
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Then she gets forced to work for McLean, and who is back for another season? DUNCAN. (In Action)
So during the un-filmed time between episodes, she basically forced him to talk to her, and sort out what happened in the past.
They get everything out of their system, and end up on kind of neutral terms. They even start roasting eachother and basically playfully being the other's biggest hater. (Similar to Duncan and heathers/Harold relationship in canon)
Courtney never gets told about Neha being his ex, though.
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Fast-forward to WORLD TOUR!! yay.
Neha plays as a girl from the start, and nothing changes much, except for the fact that london ended differently, and Neha is still in the competition.
Let's say that the love triangle does happen. So yeah, Neha is pissed, because Duncan is being an asshole AGAIN. It takes everything from her to not lash out at him.
Doesn't help that a challenge similar to Niagara Falls happens, and they get paired together. Even better, Chris found out they used to date, and decides it would be fun to expose that information to the whole world in the middle of the challenge. So yeah, it's a disaster.
Duncan refuses to be useful, and Neha is just insulting him the whole time, so at the lack of eventful situations, Chris does what the contestants love the most...
Cue a song! :D - it's a duet, similar to the greece challenge one, basically "Do what you gotta do" from descendants 3, except we take out the fact that they're father and daughter, lol. Some lyrics are different for the sake of plot.
(did i make this whole thing up because i thought it would be funny to imagine them singing it, yes, yes i did)
I love that moment from the song where they go "get over it", "I AM over it", "I'm over YOU being over it" so yeah, they both would be petty, sue them.
They sing that while having to evade lasers, booby traps on the floor, and other deadly things. In true Duncan fashion, he decides to continue being an insufferable man, acting like he doesn't really care about what happened, while they're forced to once again talk about their problems, only this time in front of a camera, -and singing-
The others are looking at them both completely astonished to the order of events that are happening, and because it can't be forgotten, of course Alenoah was pining! So yeah, we get to see Alejandro turn into a big, big, green monster. (I think there would be a segment where they show the peanut gallery's reaction, so yeah, everyone is like; "damn, wdym they're exes???"
So yeah, thats my idea.
They don't really like eachother like that anymore, but Duncan was probably acting very flirty and cocky during the whole song just to fuck with Alejandro and possibly Courtney.
......,...oh I see. You're a mind reader aren't you? Cause there's no way I was literally plotting a dunoah exes au when this popped up😭. The only difference is that the reveal doesn't happen because no one believes Duncan. Especially since he says stuff like "X is such a girl" all the time. And they're messier since let's be honest, they're both MAJOR assholes.
Pre total drama
The childhood sweethearts. Their parents were good friends and the two have been on and off again for years. At first they were good with each other but things soured over time.
This is also where Neha's self sabotaging comes from. As well as Duncan's penchant for clinging onto his exes after they break up.
They unfortunately know everything about each other despite not admitting it.
After their final break up, Duncan got sent juvie for the last time before total drama. Neha focused on graduating as soon as possible so she didn't have to see him again.
It's a lot harder to pretend you don't know someone you've known since you were a toddler, even if it's been a while since you last saw them.
Duncan knows about her cross dressing habit since they have used it before on less than legal dates- she refuses to get caught unlike a certain someone.
A hacker and a delinquent- what can go wrong?
You know how I said in another post that I headcannon them both speaking French? Yeah, they used it to flirt but (mainly) to argue. Plus Duncan picked up bits from her other languages (let's be honest, it's mainly swears and slurs). But they do tend to slip into it when talking to each other as habit.
Like you said, they did break up on bitter terms (the last one at least).
Their previous break ups had two main reasons- Duncan because he's afraid of commitment and acted like douche and Neha because she self sabotages as soon as she sees a hint of something wrong. Though to really simplify it, they just don't communicate.
And to really draw parallels to Courtney, the final straw in the fractured relationship was when he cheated on her. That's why she's mad- because he had the gall to do that when they were together when he could've just broken up with her first (like he had in the past)?!?!
Duncan also has a habit of not liking seeing his exes happy- or without him (like seen with Courtney and Gwen) as some weird validation thing so he would totally try to sabotage any potential relationships to Neha's annoyance.
Basically, a toxic relationship they let drag on for far too long.
Island
They immediately clock eachother in the island. In fact, their little interaction was them feeling the other out like "you're not gonna blab, right?" "No? why would I want them to know i dated you." All in subtext.
And yeah, Neha doesn't want to deal with him and leaves the situation (and competition) because unlike some people- she grew up. (She did not)
Out of spite, Duncan tries to actively tell everyone that 'Noah' is female but no one believes him. This is also a reason that he pantsed her, but to his shock she was wearing boxers that made it hard to tell. He got slapped for that and they argued, resulting in him eventually giving her cargos back
Neha tries to constantly warn Courtney off since she knows exactly what Duncan is like except that Courtney just takes it as "oh...Noah is jealous? Wait-does Noah like me?" Eventually Neha gives up because"it's not my problem if she wants to be stupid"
Anyways, just to make the point clear, the two are very spiteful assholes to each other.
Action
Things boil over here.
Neha gets herself a job (as 'Noah') working for Chris and totally abuses this role to exact some....revenge on Duncan.
She does also clock the beginnings of gwuncan and is not happy. Like hell is he going to cheat on another girl.
So Duncan's finding himself a lot more injured and frustrated because why are the challenges harder?!?!
When he notices 'Noah' with Chris, everything clicks and he is furious.
So he tracks her down and they argue (into a screaming match that maybe gets physical) until they come to a truce. He won't cheat and she'll stop sabotaging him. Things are somewhat peaceful after that, they still make digs at each other but they're not as openly hostile.
...
...
And then world tour happens- the same until London.
Eliminated
You know how I mentioned sabotaging relationships? Well what's better than getting your ex immediately eliminated after she trash talked a guy she's clearly crushing on just to watch the bitterness fester?
He'd probably make a comment to Alejandro about it as well after her elimination just to annoy him. Like "you weren't missing out much, the nerd's not a good lay, you should just stick to Heather, at least she isn't second hand." or "an eel...you know, I used to get told I was as repulsive and invasive as a cockroach when we were together" because who would believe the new guy and the shock mixed with hidden despair is funny
Also, the love triangle is in this one
Out of pure spite, Neha gets back onto the show and the first thing she does is throw hands (well, she insults him until they do), wig comes flying off and the two are stuck together during the wedding challenge.
She immediately allies with Courtney and Alejandro purely to spite him (she saw what he said about her behind her back...she's still friends with some of the staff after all)
Minor love triangle between Heather, Alejandro and Neha. This either ends up with Alenoah and heathney or Alenoaheather. Maybe add Courtney in- aka the biggest f you poly to Duncan.
Not eliminated
Chris is still annoyed about the coffee (and a few other things) so what better revenge than letting his former assistant stay on a team with someone 'he' just trash talked and someone 'he's' known to be incredibly hostile to? A recipe for drama!
Because of Neha still being there, Duncan is on guard.
Because of this, when Gwen goes to kiss him and he's like "no, I can't do this when my ex is on the plane, the asshole might actually try to strangle me. Again." "You and Courtney broke up already?" "What- no. I'm talking about Neh-Noah. Whatever the nerd calls her self." "....YOU DATED NOAH?!?!?!"
Tyler overhears all of it.
Of course this is what is revealed, except when Alejandro pressed Tyler into telling, he thought it'd just be about Gwen and Duncan if the glares and glances said anything. He was incredibly jealous surprised to hear two of his teammates have dated before.
So everyone finds out and Courtney is devastated, not only did her best friend and boyfriend almost kiss, but she thinks that 'Noah' and 'Duncan' met on total drama... That gets cleared up fast.
So in return of being called out, Duncan yells out "well the nerd's a girl'" which ends up in him taking the wig just to throw her under the bus.
She starts screaming at him, he starts screaming back and Chris (who had been standing there munching on popcorn) decides the episode can have two songs. Everyone else is in catatonic states of shock. They find out just how long the two have known each other. Either do what you want to do (heavily edited of course) or, or to emphasise the toxicness of the relationship- you're nothing without me...
Or, the song could be sung with Duncan and Neha in the maze thing and unbeknownst to them, everyone is watching. Tyler spilled to everyone when they heard 'Noah' calling Duncan a cheater (she didn't know about him and Gwen almost kissing) and Tyler responds with- "how did he know?!?!" But they don't even get time to dwell on it as the song bell rings. Courtney is stewing in her anger and despair during this.
Then, just picture- you're nothing without me with aggressive dancing (like a tango where they're also taking every opportunity to injure the other). The Neha reveal would be Duncan singing "and no one knows your real nammmeee" then yanks the wig off and they continue the song like that, somehow even more aggressive.
Courtney and Duncan officially break up and Neha is comforting Courtney out of solidarity (trying her hardest not to say 'I told you so') saying things like "I get it, the guy's an asshole but you shouldn't let one relationship or guy dictate the rest of your life- especially your romantic one" except...that's exactly what she's been doing and BOOM self realisation where she decides she's going to stop pushing people away because of one shitty (and very long) experience.
Courtney and Neha teaming up to humiliate Duncan in the rest of the competition (fake flirting- yes)
The whole thing gets messy. Courtney and Neha flirting with each other (and Alejandro) to piss off Duncan; Duncan flirting with Neha to piss off Alejandro, Neha and Courtney; Duncan encouraging Cody to flirt with Neha because he knows she hates it; Duncan trying to get Alejandro to flirt with Courtney to throw her, Neha and Heather off but Alejandro flirting with the wrong ex (Neha); Heather feeling left out of the weird flirting strategies and just starts aggressively flirting with Gwen to try and get everyone's attention; Owen standing there like 😳 and Sierra like 😡
Neha being very forward to Alejandro, despite it not being obvious to anyone else
I just... I just thought of something funny. Every time Duncan tries to flirt with a girl, Neha slides in there and starts subtly flirting with them too, except that only Duncan realises that she's flirting (he's used to how she works) and it's solely to piss him off. It works. Heather had a really confusing time on island - especially after her elimination.