80s dad!stan idea?
so i've seen... a couple different AUs where Dipper and Mabel are Stan's kids, but most of them set it up in such a way that the twins grow up in Gravity Falls, and while that's a very fun vibe, I think they would be very different as people with the specific and deeply strange environment of Gravity Falls around them at an early age, and also I really like the idea of an AU that preserves the vibe of wonder and mystery of it being their first summer in town... and the first time they're really interacting with Stan. But, of course, Stan is all about family, so the only way to do that is for him not to know about them until recently.
Enter: Carla McCorkle, Stan's high school girlfriend. What little we know about her is that she loves music & dancing, that the two times we've seen her she's been dressed in bright colors (colors, btw, that we've also seen on Mabel, usually), and that she dumped Stan for Thistle Downe, a hippie who Stan was convinced (possibly erroneously) used music to manipulate her. We don't know when that was, other than presumably before Stan got kicked out (though there's some solid angst potential in it being after that, it doesn't work for what I'm cooking here), but we know that the time between Stan being kicked out and the Portal Incident is "over ten years" and "ten years" depending on which lines you take as most accurate- but most timelines for the show that I've seen put it closer to 13 years.
So it goes like this-
Carla, barely 18, pregnant with her ex's kid- maybe not actually sure the kid is Stan's and not Thistle's at this point, but she has some suspicions- hears that Stan got kicked out, that he's left the state, and decides she's absolutely not telling anybody that this might be his kid, because she's sure as shit not gonna let Stan's family near her kid- sure, Stan's a bit of a wildcard, a little hot-tempered (what was he thinking, with that stunt he pulled with Thistle's car), but he's got a good heart, and she knows his dad's a hardass, there's no way Stan deserved whatever happened there, which means there's no way his family can be trusted to treat her baby decent. (Well, maybe Stanford, she always thought he was nice- a bit odd and a bit awkward, but Stan adored his twin, so Carla figured he must be more fun when he's not trying way too hard to be polite to his brother's girlfriend about how much he'd rather be studying than talking to her. At the very least, she'd consider trusting him with this in an emergency, but she doesn't expect to need to.)
Carla, over a decade later, having a bit of a rough time and neck deep in an increasingly deteriorating marriage to and probable divorce from Thistle (to keep the twins' parents-are-divorcing angst subtext), gets a call from a cousin back home (one of the only people other than Carla and Thistle that knows exactly who the twins' dad is- the twins know it's not Thistle, but not any details beyond that, and they're curious but haven't found anything out yet. For context, I'm thinking Thistle has raised them but is a very distant and disinterested stepdad, he's very much just the guy who was there, barely willingly) telling her to check the obituaries and (for crying out loud Carla) figure out how to tell the kids, because Stanley Pines' funeral is next week.
Carla does not tell the kids (yet). Carla, being a sensible and relatively compassionate woman, sees that the contact info regarding the funeral in the obit is for Stanford Pines and immediately calls to check on him. (It's not irrational, and she's not thinking about how if she'd said something sooner, things might be different, and it definitely isn't anything to do with the tight feeling in her chest right now- and Carla is maybe just as good at lying to herself as any Pines is because she believes all of those until he answers the phone. She knows that voice- it's sharper, deeper, rougher, but she knows the sound of him, and Stanford never sounded like that, which means.... something. Mostly, it means there's still time.
"Why are you holding your own funeral?" she asks, in response to the gruff hello he'd answered the phone with.
"Who is this?" he snaps back, sounding... nervous?
"Carla. Calling to offer her condolences to her ex's brother, who must be going through a hard time right now, after his twin died, except apparently you're right there, Stanley, so answer the damn question."
"....shit.")
....the problem is this is where I can't bridge the gap between the angsty bit and the bit where the kids stay with Stan for a while, but somehow they end up there for the summer, and much of the plot of the series plays out similarly, just in the early 80s instead.
(also possibly Stan and Carla end up back together because I'm a sap and also because, let's face it, Mabel would play matchmaker.)