Work Text:
"Grunkle Ford!"
Ford can hear Dipper speaking, but he doesn't have time to listen. He marches into the Shack, takes a quick look around to see if anyone else is nearby; when he sees no one, he starts heading for Dipper and Mabel's room. He can feel Dipper's heart hammering in his chest, feel his own thundering heartbeat, and the sounds almost distract him from what he's doing. But he cools his mind, enters the room.
"Grunkle Ford, please stop!"
Ignoring the boy, he rests Dipper down on his bed. He doesn't waste any time here, grabbing Dipper's vest and pushing it off his shoulders. When Dipper squirms against him, Ford leaves the vest tangled around his wrists, and does the same with his red shirt. When Dipper's upper body is exposed, Ford takes a moment to examine it, noticing how Dipper's nipples have hardened into tiny, tight knobs. He brushes a thumb over one of them, making Dipper shiver, therefore confirming his suspicions.
He hasn't been fast enough. The cursed birch trees they encountered earlier have left their mark on Dipper, blown their pollen at him despite Dipper's claims of the contrary. Now there is just one thing left to do.
Ford starts to pull the button of Dipper's shorts open.
"Grunkle Ford, this isn't you!" Dipper tries to kick at him, but their earlier struggle in the forest has left him with a hurt ankle, leaving him partially immobilized; it's easy for Ford to just push his leg to the side and pin it down with his own knee. Dipper winces, but keeps talking: "Grunkle Ford, please just listen, you don't have to do thi-"
"Yes I do, Dipper." Ford pulls the zipper down and then the shorts themselves, tugging them all the way down to Dipper's ankles. He takes a moment to take Dipper's shoes off, careful not to hurt his sore ankle, but leaves his socks on as he throws the shoes and the shorts on the floor. He repeats the process with Dipper's underwear. "You have been exposed to sex pollen. It will soon take over your brain, but there is one thing we can do before that."
"Grunkle Ford, please!"
Ford flips Dipper over to his stomach, pushing a knee between his slender thighs. He rubs his thumb down the crack of Dipper's ass, finding a small opening between the tight cheeks.
"Unfortunately, there's no other way," Ford says. "The only way to fight the pollen is to give what it wants, Dipper. I must fuck you."
"Grunkle Ford, it doesn't work like that!"
Ford can't help but chuckle. Dipper is a very intelligent boy, but Ford has been doing this for a long time and knows these things. He pushes his thumb into Dipper, making him groan; he starts thrusting with his thumb, moving it in and out in a slow, sure rhythm, going a little deeper in with every little thrust. Dipper arches his back, moaning loud, and Ford can't resist leaning over to kiss Dipper on his small shoulder.
"Grunkle Ford, please!" Dipper pleads, struggling as Ford settles on top of him, pushing his thighs apart with his knees. "You're the one who's been exposed!"
Pulling his thumb away, Ford reaches for his crotch to undo his own zipper. His cock is hard and leaking when he takes it out, and he takes a moment to gather pre-come into his fingers in order to rub it against Dipper's hole; when it turns out there isn't enough of it, he spits in his palm and rubs that on Dipper as well. Neither make ideal forms of lube, but in lack of better substances they will have to do. After he's done preparing Dipper, he takes his cock into his hand and guides it to Dipper's entrance, starts to push in.
"The more you relax, the better it will be," he tells Dipper, wrapping his arms around the boy's slim body as he rolls his hips forward. Dipper has ceased to talk, making small, strangled sounds as Ford enters him, tense despite Ford's words. Nevertheless, Ford continues to be as gentle as he can be, holding back from simply slamming into Dipper like his body desperately wants to. Instead he works his way in slowly and patiently, until his balls are resting heavily against the silky skin of Dipper's ass and Dipper's legs are shaking against his own.
"Just relax," he says one more time, then starts to thrust.
Despite his pained gasps and groans, Dipper does relax, his body yielding to Ford as Ford fucks him. He also doesn't resist when Ford reaches down to kiss his cheek, to lick his neck, when Ford's hands roam over his chest and ribs before grasping him lightly from his throat. Dipper does protest when Ford reaches down between his legs, even though his cock is hot and stiff against Ford's hand.
"Don't," Dipper says, but doesn't object for a second time when Ford takes him into hand and starts stroking him anyway.
When Ford feels his orgasm get closer, he slows down his thrusts to make sure that he's still in Dipper when he comes. By the time he climaxes, he has gone absolutely still, buried to the hilt within his grand nephew as his cock jerks and twitches and empties itself inside the boy. It takes a little longer for Dipper to come, Ford's strokes turning into rough, hard yanks until Dipper is finally twitching in Ford's hand too, wetting his fingers with semen.
Ford collapses on top of Dipper, his breath coming out in heavy pants as his eyes slide shut. Slowly, his mind clears up.
His eyes snap open.