This feels a little pretentious and… fairly embarassing, but! It sounded kind of fun and sometimes you just have to be your own hypeman. Not to mention, as the artist, I can nit-pick my own details all I want and people can't really tell me, "well, maybe the curtains are just blue," so…
An (unnecessarily in-depth) analysis of my own drawings!
Part one: Stan
The drawing is set up, basically, as stan laying down on the front seat of the Stanleymobile, surrounded by trash and looking despondent. If you look past him and out of the car you see a pine forest in the background, as well as a shadowed creature looking through the cracked window and pressing its palm against the glass. If you look away from him and towards the front of the car, you see bill's eye glaring back from the rearview mirror.
Without the malicious figures peeking around the edges of the piece, those woods Stan has parked next to could be anywhere. However, the strangeness of the monster coupled with the recognizable features of Bill Cipher give a pretty strong hint that Stan might be somewhere in the forests of Gravity Falls.
The creature does not have an expression, and it's body language is fairly nondescript. It might not have bad intentions, it just comes off as foreboding in its inhuman nature and in the fact it has come up to stan without him realizing. However, its eyes glow almost yellow if you look closely, and the red tinge to the drawing don't bode well… maybe the door being unlocked wasn't great idea.
In contrast to his blank faced companion (who is potentially acting under his influence,) Bill's eye is pretty emotional. He seems disturbed, perhaps frantic or enraged, and has a definite air of malice. Considering Stan seems to be under direct threat of whatever is happening, you could assume that he would be the subject of whatever ire is possessing bill— and he probably is— but if you look at Bill's iris, it seems as though it is pointed away from Stan and towards the viewer. Well, WHY is Bill so upset? If Stan is truly near Gravity Falls, then that means he is also near his brother. His brother, who is currently under the influence of Bill in some capacity if Bill is present and Stan is still living in his car. If it's warm enough for the window to be cracked and Stan to roll up his sleeves, then that must mean Bill's influence hasn't yet been corrupted by the reveal of his betrayal.
And he wants it to stay uncorrupted, thank you very much.
You put bill, stan, and ford in a room, and bill is thwarted, every time so far. The first time he severed Bill's influence in his portal's dimension by shoving his anchor through it (and granting ford the end of the benefit of his possession, as well as the means to eventually cut it off permanently.) The second time, the stan twins worked together and eradicated him completely. Preventing Stan from enacting a third and premature example of this formula is something Bill would probably find essential. Cutting Stan out as a variable entirely would probably be even more so.
He doesn't want his plans interrupted, he doesn't want to lose, he doesn't want to see his carefully wrapped manipulation undone. He wants to control the narrative. The only ones who would understand there is a narrative to control is Bill himself, and us as the onlookers. If this is truly a hit he planned or encourages, he likely wants it to go off unsolved by a certain genius nearby. And we are witnesses to both the crime and his involvement.
Stan is unaware of both this and the general danger he is in, gazing up and pointedly away from both threats. Despite this, he resembles his assailants by wearing a yellow dress shirt. It both matches the color scheme and marks his involvement with Bill (and perhaps ties him to his brother.) However, the shirt is stained and torn, and he has a suit jacket draped over the seat beside him. This is an undershirt, hidden in majority by the flashy ensemble he adorns himself in when socializing. His connections are not those he is aware of, or are at least ones he pretends not to be.
Speaking of stained and torn, the entirety of Stan's car and Stan himself are less than kempt. His hair is scruffy and mussed, he is unshaved, and he sports various bandages and a scar across his knuckles. The Stanleymobile, in turn, has torn unholstry, scruffs and cracks across the interior, cracks and smudges on the glass, a rips in the cieling's canvas, and of course trash littered everywhere.
The car mirrors stan in his physical state, in his depressive disposition, and in his inaction to improve his living conditions. He hasn't changed his lifestyle, he hasn't cleaned himself or his car, and he hasn't turned around to see that he is about to be attacked. He's stuck laying down, stewing, and it could be his downfall.
Some of the clutter is generic, and some of it gives a direct view into Stanley's personal life. A hefty speeding fine and a ransom note rest in the glove compartment with one of his fake ID's, as well as bullet holes in the windshield. His life of crime that he hopes will bring him to fortune and success, and eventual reconciliation. Just below, a paper of his company's finances, a split credit card, and a crumpled and crossed out note to his estranged brother. His failures in said hopes. Under the seat he rests on poke out a first aid kit, a bloodied tissue, and an empty bottle of booze. Evidence of how these failures impact him.
On Stan's self are only two pieces of the car's inventory. A lottery ticket and a lighter— representing his gambling nature and his choice of damage control.
He keeps the lottery ticket in his breast pocket, as his hopes rest by his heart.
If you've read all this, I'm in love with you, and also--
This drawing is placed after the one with Stan, with the background pines from the first now illuminated by the dawn in full view. A little ways into the treeline, Ford kneels next to some strange tracks which continue behind him into a clearing, where they stop— or rather, start— at the open door of a seemingly abandoned red car.
Part two: Ford
At the edge of the piece, a familiar dark figure is pressed into the branches of a tree.
In reference to the previous piece, in can be safely inferred that the tracks and the car are the result of whatever it was that was watching Stan making a move and dragging him somewhere into the woods, quickly enough that the door to the car was left wrenched open, and presumably by his legs as the marks seem to be desperately clawed into the ground by his hands.
Ford has probably stumbled across the scene the morning after Stan was attacked, as the various pieces of trash last seen within the car haven't been blown too far away. Likewise, the tracks are fairly consistent and deep, which would require pretty soft earth to not damage the fingers and nails that made them and leave behind blood. The slightly muddy earth has not been dried over a long passage of time, since Ford bears it on his boots and knee as he kneels.
Ford, in his examination, does not seem to realize what, exactly, has happened. He is still within the treeline, a ways away from the clearing and his brothers car, and facing the opposite direction. While he looks at the scene in front of him, his expression is of curiosity and mild concern, not horror or fear. He holds Stan's lighter in his hand, and has at least the lottery ticket near his feet. He knows— or at least suspects— a person has been involved in whatever has happened, as well as a potential anomaly, but he doesn't seem to have the urgency expected if it was someone he knew. Had he seen the very distinct and personalized car behind him, he would have surely known it was his brother who had been attacked.
Will he turn around and see?
The trees frame the golden sky in sort of a triangular shape, and the bright sun that hasn't yet risen fully from the horizon is partially blocked by the silhouette of a far off tree. It looks almost like an eye, whose slit pupil is glaring in Ford's direction.
Bill does not want Ford to find his brother. Bill does not want Ford to know his brother was around at all. Ford happening to venture out this far at this particular stretch of time is exactly why Bill wanted Stan out of the way as he parked in his car the previous night. Stan was taken, Bill's plan was a success, and now it might be for nothing.
But more than Ford discovering Stan was there, Bill needs Ford NOT to discover that he might be the reason Stan isn't anymore, for that would be sure to cost him his prize devotee.
Bill gazing on in a much more abstract way is distinctly different from his actual visage being visible in his cameo with Stan. He's played his cards already, now he has to wait for the other players turns. More than that, Ford is in shadow, the light of the sun blocked by the trees around him. Whatever is happening now seems to be out of bills sight and thereby power. However…
If we take a closer look to Ford, we see that he is wearing a red sweater. In fact, in contrast to the yellow-green that surrounds him, he is mostly red toned. He and the Stanleymobile both contrast the scene this way, and it shows his direct tie to his brother in this situation. If we take an even closer look than that, we see a yellow button up beneath it, and on the side of Ford's satchel, there is a particular triangle embossed into the leather of a pouch. It has a sprig poking out of it. Bill is still in Ford's life, his influence is alive and well. In fact, Ford might have already given him the ability to possess him. Regardless of if Bill gets his way here, he could very well still provide a large threat both by use of Ford's mind and body.
The danger isn't over.
Off to the left hand side, the same creature who stole away Stan surveys the current scene from the shadows. It isn't just hiding— it's hand curls around the branches to push them aside. It doesn't want to escape, it wants to do something. Maybe the same something it did the night before.
Right now Ford's feet point him perpendicular to the trail. He is at a crossroads.
If Ford was to follow the tracks where they lead, he might find his brother at the end of them. He might also not have the urgency required to get there in time for it to matter. It all depends on if his goal would be to help whoever might've been attacked or just observe whatever it might've been that attacked them without having any stake in the matter. In this point of time does Ford navigate himself in the direction of hero, or researcher? When he gets confirmation of Bill and the portal spelling doom for the world he decided to forgo his health and safety in order to stop them. He also refused to heed warnings from his fellow scientist when he was given good reason to believe they were dangerous before the outright confession. Maybe in his heart he fancies himself for the good of others, but in this stage of life Ford does not always prove to have the instincts for it.
On the other hand, if Ford was to turn around and see the car, he would get the full picture and be equipped to make the right decisions with the right levels of concern. He would also turn his back to the creature and possibly be attacked himself. He would spend even more precious time away from where Stan actually is just figuring out he's around, and maybe even cloud his judgment when tracking down Stan with worry, leaving him open to mistakes. By the venturing out into the clearing to investigate, Ford would also be directly in Bill's light.
The car, in all it's cherry-colored glory, is a red herring.
We see the lottery ticket, that which represented hope, resting ahead of Ford. If he wants to make a difference, his best bet is to not focus on the past and press forward.