The #1 Scott x Mechanic shipper

OKAY. So let's start with a bit of background for people who aren't familiar with both shows. Thunderbirds Are Go is basically a show that's set in the year 2060, following the Tracy family and the work they do as International Rescue. The name is pretty self explanatory, they're a rescue organization that operates globally. Their vehicles are called the Thunderbirds, and their equipment is advanced enough that they can respond to emergencies that might otherwise be impossible to get to in time or would be hard for normal response teams to handle. Generator Rex takes place in a sort of post-apocalyptic setting; we start the story 5 years after the Nanite Event, which spread microscopic machines known as nanites across the globe. Every living thing on Earth was infected with them, and they can randomly mutate their host into an "EVO"- an acronym that stands for "Exponentially Variegated Organism." A good percentage of the EVOs end up becoming a danger to the people around them, so a paramilitary organization known as Providence was formed sometime after the Event to handle these EVO attacks. The main character is an amnesiac 15yo boy named Rex, an EVO working for Providence that can build machines out of his body and "cure" some other EVOs, reverting them to what they were before their mutations.

So, with that out of the way.

There's two main ways I've considered a crossover au in a combined universe:

Not much is changed about the plots or relationships as they are in their respective shows, but their settings are melded together as is and their stories take place side by side with some overlaps where they could easily fit together. For example: International Rescue would be very well suited to help in Gravity when the space station is crashing- the only way Providence could get there in time was by putting Rex on a space elevator that was not designed for people and was explicitly stated to be lethal to a regular human being. It's just pretty easy to imagine how iR could be helpful in some of these situations, and I could see Rex helping them out as well from time to time. We've seen him voice that he likes being able to use his powers for something other than just fighting for once, let's give more opportunities for that! As is, there's already plenty of interesting things to explore- from how the Tracys would perceive EVOs, how they'd adjust to the Nanite Event (which, btw, with the way I've aligned the timelines, would take place roughly a year after Jeff's disappearance :3), to their relationship with Rex and their opinions of Providence. I love thinking about how they'd be incredibly concerned about this kid and the way he's treated- the way he's referred to as a "weapon" both by others and himself. He's working for an organization that has a "cure, contain, or kill" protocol for handling EVOs, and he is one. He's canonically mentioned multiple times that he isn't paid, and especially in the beginning he's very isolated. Everyone around him works for Providence- even when he gets his first friend, Noah's actually a spy for White Knight in the beginning so he's still a part of Rex's life that's controlled by Providence, at least at first. I don't think they'd have the power to get him out that situation, but I definitely see them trying to reach out to him where they can. Plus Alan is around his age and I think they could be good friends. (I do wanna be clear that Rex does have people in Providence that care about him- Holiday and Six do what they can to take care of him, but at the end of the day they still have to their jobs. Really, harm reduction is all they can do. The Tracys aren't gonna know these details from the start though) There's also the fun possibility for TAG characters to go EVO- we'll get into that more in a bit. (Gladys would be a fun one though; Ned's plant friend can appreciate him in return and take care of him the way he's taken care of her :D) Also: iR rescuing EVOs!! There's a percentage of EVOs who retain sapience even after turning (or, in the case of animal and plant EVOs, can sometimes develop the ability to communicate with people), and it'd be interesting- especially in the earlier days after the Nanite Event- to see it click in real time for them that...oh. These aren't just mindless monsters. They're still people. We're talking about a family that stuck to their values about saving lives even when it was the life of their worst enemy- any initial fear once they show up and realize what exactly called for their help wouldn't stop them saving them the way they would anyone else. There's also specific character interactions that would be fun to see, but for the sake of keeping this a manageable length (the original draft of this post was around 2k words, and even after revision it's. Not much shorter tbh) I will leave that for another time.

This option is, admittedly, the one I've explored the most with my friends 'cause it's really fun to me. Honestly, it's just a really self-indulgent AU where I give Rex a bit of a better upbringing because this kid is already put through the ringer enough as it is Basically, I had Scott find Rex as a kid instead of Six. It wouldn't be unreasonable; if iR was there to help with the evacuation during the giant mech rampage, or on-site ready to search for survivors in the aftermath, it would be entirely possible for him to find Rex in the rubble. And now Scott's got this 13(-ish) year old kid that he ends up taking home with him, 'cause. Well. What else is he gonna do- turn him over to Providence? Hell no. Before Rex their protocol was only "kill or contain", and I can't see Scott being willing to hand a literal child over to them, EVO or not. SO. Rex Salazar-Tracy AU my beloved <3. International Rexcue AU, if you will. Giving Scott a son and it's one that can build his own wings and fly, good luck <3. Also he may or may not turn into, y'know, a giant fuck you robot if put under enough duress. Whoops. No one is really surprised when Scott brings a kid home. They don't know about the mech thing at first, but it's pretty obvious once they actually see Rex's machines. Doesn't really change anything about the decision to raise him though, but it is something they gotta watch out for. It's just fun to explore what Rex's life would be like if he hadn't ended up with Providence, but with someone like International Rescue instead. He fits right in with the Tracys; he's already got some similar values to them ("Why...why would you help someone like me?" "Because a person is a person, no matter how screwed up they are.") and there's ways he reminds me of some of them (mostly Scott, Gordon, and Alan) in terms of personality, behavior and mannerisms that just. Makes it pretty easy to slot them together It is also fun to make them wrestle with the decision of having to hiding the fact that there's a "cure" (Rex) from the world in order to protect him, because I can't see them being willing to exploit a kid like that, and how the world fares without any concrete sign of hope for a little longer. And also the guilt of knowing that there are people they could have saved, but didn't, because it was at a cost they weren't willing to pay :). At least until Rex is old enough and makes the decision himself (because I do still think he'd choose to help people), for 3 more years, the world has no "cure". Also: Virgil and Kayo are EVO now :). I thought it'd be fun to make Virgil a werewolf EVO like the ones we meet in Night Falls that shift from a human form to an EVO form during the night, and Kayo is now Goop™. Originally there weren't more details about how she went EVO, but since Silver described it as a "corrupting goop" when they designed her, I went "heyyyyy that reminds me of something" and now she is, specifically, made up of the same substance as the unstable nanite goop from What Lies Beneath, thanks to getting submerged in it in this AU's version of its events. (EVO Kayo art is by @xsilverberryx)

Now, this obviously isn't everything, but this is already a long post without getting into all the details so here's a few misc. Rex adoption au art/memes and we'll just leave it here for now

So, Generator Rex is a sci-fi cartoon set in a sort of post-apocalyptic universe- the apocalypse in question being something called the Nanite Event. The Nanite Event was an accident that happened 5 years prior to the start of the show that spread nanites across the globe, so now every living thing on Earth is infected with them. Now, these nanites are usually harmless- just having them in their bodies doesn't hurt people. However. They can, at random, mutate their hosts into what they call an "EVO"- an acronym that stands for Exponentially Variegated Organism. This can happen to anyone at anytime. A few examples of EVOs:

The complicated thing about EVOs is that a lot of people lose control of themselves in the process, but not always. But when they do, it often leads to destructive rampages. Due to the danger a lot of EVOs present, a paramilitary group called Providence was formed to deal with them- which is where Rex comes in. In the show, Rex is Providence's "secret weapon"; a 15 year old EVO that can actually control his own nanites, and use them to build machines out of his body, communicate with machines, and most importantly- "cure" EVOs, reverting them back to who/what they were prior to the mutation (he can't cure all EVOs, though, the existence of "incurables" means that there's still a need for an alternative cure).

Anyways, this is Rex normally.

However, the day he was found, he was...well. His nanites have a sort of, last resort self defense mechanism- in extreme enough situations, they will take over to protect him. And the result is...well. You know

Underneath it all though, he really was just a kid when he was found. A kid with the potential to be incredibly dangerous, sure, but a kid nonetheless.

Providence reacts to him...poorly at first, to say the least. But in the end, he's at least a useful asset in this "war", and so he's kept around and trained to fight other EVOs, and cure the ones he can. "So he's a child soldier and a living weapon" yes. Yes he is :D.

Generator Rex is a long running hyperfixation of mine, and 'cause I was getting back into it when my friends first introduced me to Thunderbirds Are Go, I'd had some thoughts brewing for a crossover even before I'd finished the show. I mean, TAG is pretty easy to work with when it comes to crossovers imo- hard to imagine a universe where International Rescue wouldn't be handy to have around- and Generator Rex is just a fun concept, especially if you want to play around with angst of the body horror variety.

When it came to the adoption au, there was actually a couple different ways I considered approaching it- the current iteration is the one where Scott is the one to find Rex instead of Six; both International Rescue and Providence would have reasons to be on the scene of such a massive EVO attack after all, and of course Scott would take him home- Providence was a Kill or Contain organization before Rex was found, he couldn't in good conscious hand a kid over to them (EVO or not), and it'd be hard to trust anyone outside of iR with the safety and wellbeing of someone like Rex, so...yeah, the kid's family now. At least until they can find Rex's family- if they're still out there somewhere; and if not...well, he'll still have a place with them.

The alternate route, however, is one where Six is still the one to find him- except he and Holiday actually manage to hide him somewhere safe like he'd intended before any found out what Rex was. And who safer than International Rescue, whose whole thing is saving anyone who asks, regardless of who they are?

(Option 1 won out though, because of course "the earliest memory Rex has is being saved by Scott" is such a sweet concept...and of course the accompanying joke that can be made about him practically imprinting on him like a duckling XD)

I will also link previous posts where I've talked about the adoption au- first is the answer to an ask about a crossover in general, and then this post here where I answered some more questions about it.