Lumberjack option so far:
The AU, tis beautiful in its angst. Consider the alternate path of...the lumberjack.
3 years after that summer, Stan's working at the docks full time (filbrick pulled him out of school and got him the job under the table a year after he came back from GF)(He's 15 here) when filbrick gets a heart attack in the middle of stan finally standing up to him. Police investigation clears stan of fault, but the only family who can take him now are in Gravity Falls(Caryn moved out there after the divorce, but she's got her hands full w/ Shermie. It makes more sense for Stan to move in w/ his Great aunt and uncle)
So stan's f-ed up mindset in this is something along the lines of 'Grauntie Mable, who I like and respect, told me I am selfish and I need to stop acting that way and put everyone else's needs ahead of my own.
Pa, who I respect and care about, told me my only value was in producing money for the family. He said I was an unwanted child, and money is the only way to be part of the family.
Therefore, if I stay emotionally out of the way (no more suffocating) and provide for the family, I will be permitted to be part of things. Clearly, this is what Grauntie Mable has successfully done- the unwanted one who provided w/out suffocating, and is now a loved member of the family. This also explains great uncle mason's distaste for me- he knows I haven't earned enough to be part of the family.
Everything makes sense now!'
Not quite as bluntly as that, but you get the idea.
So Stan gets a job w/ Manly Dan's crew, doing as many hours as they'll let him over the summer(he arrived in Gravity Falls shortly after school let out for the year) and getting to be friends w/ Wendy, who's a few years older(not that she knows that, Stan's a bit on the smaller side at present for the lumberjacking crew but two years of dockworking leave him looking somewhat qualified for logging.)
This is the best summer Stan's had in awhile-he's making enough to pay for room and board and start to pay for the summer he stayed with them. He's even able to save a few dollars here and there for moving out in another year or so when he turns sixteen. If this keeps up, he might actually be able to get back on decent terms w/ his family! (just dont think about what happened to pa)
Said family, knowing none of this, barely see Stan at all over the summer (Ford's not exactly happy his brother not only doesn't want to catch up, or hang out, or even talk to him, but also won't share shifts in the Shack! He's had to do both their shifts all summer while Stan disappears to hang around town and...flirt or cause problems or...something!)
Dipper and Mable are increasingly convinced Stan's acting out after the sudden death of his father, but whenever they try to talk to him he just runs off! They're convinced he's joined up w/ the local Awful Teenager Squad, but can never get any answers out of him.
Things fall apart the first week of the school year, when Wendy spots Ford in town, mistakes him for Stan, and they do a whole little comedy of errors where Wendy makes assumptions based on her current knowledge and Ford refutes them w/ annoyance
(Stan!
What? No, I'm Ford, Stan's brother!
Oh, do you work in town?
Huh? No, I'm a junior in high school!
Oh, you're Stan's little brother!
Excuse me?!? We're twins, and I'm Older! By fifteen minutes! )
Wendy assumes the Shack must be doing poorly, finds out no, they're fine, asks stan about his schooling, gets told he was pulled out to work (when he was 14) and is left with a lot of questions and an old pair of twins to ask them to.
This is where Dipper and Mabel find out not only has Stan not been attending school, he's not registered to attend and that's why they haven't been notified of his truancy. Because he was pulled out two years ago. They ask Ford, he knows even less, and when everyone goes to confront Stan-
He doesn't see any problem. Why are they surprised, of course Pa pulled the dumb kid out of school. He's more useful working. Tell them? He thought they already knew, Pa said they had agreed with him when he told them about how terrible Stan's grades were on the phone. Anyways, why complain? He's making enough for room and board, and he should be out of the Shack on his sixteenth!
Added notes on the Lumberjack Option:
Wendy goes to Stan, tells him she saw his brother in town and thought it was him. Stan is delighted to tell her about his twin brother (its the most she's ever heard Stan say in relation to himself- he rarely speaks and is instead considered a very good listener- and its not even about Stan.) and what a great guy he is (he put up with Stan for twelve years with only minor complaints until the end, that's better that anyone except his parents managed, and they didn't last that much-don't think about it) and how he's graduating early, and-
Wow, says Wendy, you must be even smarter than him to have graduated even earlier!
Stan bluescreens for a few seconds, trying to compute that idea before blustering his way through an explanation.
(Its hard to explain to others how different Stan is from his twin without it hurting. He may have accepted it, but he still can't say aloud that he's worthless.)
He says he left without graduating a few years back, better to get a job and be making money than just sit in a classroom all day.
"And your uncle was okay with that? He used to lecture every teen in town on how we need a diploma to get anywhere in life!"
(Great-Uncle Mason has made it clear in the past that Stan's...too much and not enough.
Too much noise (jokes told no one laughed at, shouting greetings only to be shushed),
too much anger (bullies beaten up-Stan gets scolded for 'rising to their provocations', anomalies try to hurt them-Stan gets scolded for coming back injured),
too needy (clinging to Ford and getting increasingly pushed away as the summer goes on and Ford comes into his own, trying romance after romance and seeing nothing but failure(no one loves Stan but family, and even they have limits), Grauntie Mabel taking him aside just hours before Ford decides to stay and telling him how selfish he's been this summer and how worried she is that he'll push away his loved ones if he keeps being so self centered!
He needs to let Ford have his own friends and his own life- Stan can support that, right?)
Not useful enough (a money drain for the family)
not interesting enough (or Carla or Suzie would have stuck around) not smart enough (or Ford would actually want to spend time with him).
Pa and Great-Uncle Mason are just the only ones willing to say it to Stan's face.)
It wasn't like he would have succeeded anyways, Stan's too lazy! And dumb!
School's useless for a guy like Stan anyways.
---
Wendy doesn't go straight to Dipper and Mabel- she's not super close with them, and it seems kind of weird to immediately be questioning two people she doesn't know well on their financial status and treatment of their children.
Her dad, on the other hand, is a great source- except that he has no idea what's going on either and is fairly concerned about an underage child working in an industry as dangerous as lumberjacking (does he need parental consent forms? Is this anywhere near legal?)
So you get Manly Dan needing to let off some steam and talking about it with his boyfriend-the mayor. Who is, on the one hand not going to let Dan get arrested, but is also very worried about the Pines family finances (isnt the mother living on her own with the youngest son? Is that why the second youngest is working, to try and provide-oh, its so sad! Well, it can be fixed! These Jersey people have never really had to face the hospitality of a well-meaning small town before!)
And while waaay too much over the top friendliness and help prepares to descend on Caryn Pines (who is doing fine, thank you for asking. It's a pity her sons don't come and see her more often, but Ford is always running around with his friend and Stan is probably doing the same with his! he's still adjusting, heaven knows Caryn had to when she moved here! It would be nice if he would at least come to family dinners though)
Manly Dan and Mayor Cutebiker appear at the door of the Mystery Shack with a bunch of paperwork and some friendly (and once it becomes clear Mabel and Dipper know nothing about Stan's life at present, unfriendly) questions!
Dipper is adjusting his second favorite microscope when the knocking at the front door grows too loud to ignore.
When he answers, annoyed at being pulled away from his research into the composition of fairy dust, its to find Manly Dan and the mayor on his stoop with a large packet of paperwork.
"Hiya Doctor Pines! Sorry to bother you, but there's a tiny issue we need you to sign off on! Can we come in for a sec?"
The mayor smiles at Dipper as he lets them into the kitchen, Manly Dan dwarfing the table as he sits.
"So, I just want to assure you, Dan had no clue you hadn't filed the Oregon authorization papers, and the second he noticed, he called me, so no one should be in trouble."
"What?" Dipper frowns.
The mayor laughs awkwardly, patting Dan's shoulder. His expression hasn't changed this whole time from a frown.
"Well, you know how Stan's been spending the summer out in the woods with Dan's lumberjack crew? Wendy mentioned it to Dan and he came and got me, and-"
Dipper laughed, "Oh yeah, Stan's been a bit of a handful this summer-never around, none of his chores getting done. We didn't know he was bothering the lumberjacks though! If he's caused any problems, we'll be happy to give him a good talking-to when he gets home from school. Ford started up with his college level courses last week and he's already top of the class, did you hear? We're very proud."
Dan and the mayor turn to look at each other briefly before turning back to Dipper with much more concerned expressions.
"Doctor Pines, are you saying you have no idea what Stan's been doing this summer?"
"Well, his father died in May, so we were giving him some space to breathe. Mabel and I are always available for him to talk to, but he's just not ready yet, I suppose."
Another significant look. Dipper is getting tired of significant looks that aren't directed at him.
"Look, just tell me what Stan did, and Mabel and I will deal with it. We'll find him an after school job, something to teach responsibility. Axolotl knows he needs some."
Things went downhill from there.
Actually, now that I think about it, Stan's confused- but so is Dipper.
Dipper never noticed any issues-he got back, hugged Mabel, met his lovely great-nephews, and just...clicked with Ford's love of anomalies. He cares about Stan, obviously, but Stan's still young and in love with all the dumb things he and Mabel grew out of.
(That he grew out of naturally, and that Mabel left behind in a panic, desperately trying to keep her brother in her life as he wandered into adulthood)
They just don't have anything to talk about yet! Still, Dipper loves Stan. He thought that was obvious.
(It was not obvious to Stan, who saw his great uncle clearly prize intelligence and anomaly over everything else. Who never spent any time alone with Great Uncle Mason unless he was being punished.
Who believed Great Uncle Mason saw him as a nuisance at best, a leech at worst, only confirmed at the end of summer.
Stan doesn't particularly like Mason. He understands how his uncle is trying to get the useless one to do something right for once- hell, he even agrees!- but Grauntie Mabel at least showed she cared about him even though he wasn't worth it. Mason looked at stan like he was a tripping hazard.)
Sure Dipper's not as close to Stan, but they're family! Of course they love each other!
-Dipper sees none of the cracks in the family until half the town is on their doorstep, offering solutions for a problem he didn't know he had.
-He's been sort of protected from the consequences of his (lack of) actions/understanding by the family up until now- Ford hero worships him, Mabel puts his judgments ahead of her own for the most part, and Caryn is still extremely grateful for Dipper and Mabel's help getting set up.
-This is his wakeup call, where everything starts falling apart as it becomes clear he's only been looking at appearances (how many times has Mabels life fallen apart without Dipper paying enough attention to give her support? How many times has he assumed Ford's thoughts were the same as his own and moved forward without asking? Is Stan selfish?)
I see this leading to Dipper using time tape to try and fix a flashpoint moment, but increasingly seeing it wasn't just one moment that led to this, and it isn't just one person who's been affected. Think time traveler's pig but for stan and ford vs the future, where no matter what dipper tries to change-he can't. Offer to let both kids stay in gravity falls? stan doesnt want to be a burden and turns him down. Tell mabel she isn't selfish and is a great sister? She assumes its b/c of how much shes changed herself and is only more eager to pull stan aside. Ask ford to check on stan b/c dippers worried about him? Stan covers it up, and ford takes it at face value, like he has all summer.
Every day ends with ford celebrating his apprenticeship and stan disappearing . when dipper finally follows him, three to five loops in, he finds stan crying on the roof. They talk, it sucks, but eventually stan tells dipper how everything's gone wrong this summer and going home wont help anything b/c his pa hates him.
Dipper tries to brush it off, but stan shouts about the three dollar sign incident, then says
"And next time, Ford won't be there when I come inside. I dont want to put myself back together alone."
Dipper is absolutely ready to just keep stan here and now, live a happier three years, when the time police show up and reset everything (no blendins game here, no globnar). Dipper has to go three years ahead, nothing gained except for an understanding of stan and a lot of sympathy.
@shanklin