So this was posted on my AO3 for a very long time. It's been competed for months now and I thought I should just go ahead and move it over onto here already.

This is a very much NSFW fic (almost every chapter) so if you don't like triangle fucking I suggest you click back now.

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Triphile

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Dipper had been looking forwards to trigonometry.

He had been looking forwards to it for a very long time, actually. He had always been one to be excited by the prospect of learning new things, especially if said things had to do with mathematics.

Numbers were simple. Numbers were easy. Numbers made sense. Not like people, not like emotions, not like all those other complicated things his sister seemed to be content to wrap herself in.

At least, that's what Dipper had thought before sitting down at his desk and cracking his trig book open for the first time.

Dipper was all too aware of the people around him, shuffling through notes as they listened to the teacher drone on and on about something or the other. The orchestra of pencils scratching against paper was monotonous and did nothing to distract the heat pooling in Dipper's gut from the sight of those three sides put together in his book in a simple diagram.

Three sides. One, two, three.

Numbers were supposed to be simple. They were supposed to be easy. They were not supposed to cause his cheeks to flush red, for his mind to short circuit, and for that all too familiar searing to scorch his insides.

A bead of sweat dripped down Dipper's forehead, landing right next to the picture of the triangle in his book.

Dipper shifted in his seat, glancing around. For once, he was grateful to be sitting in the back row and smashed into the corner.

The kids surrounding him weren't giving him a second look from when their original blank eyes had scanned him when sitting down. They continued to sketch away in their notebooks, some much more focused than others.

Good. No one was seeing his reddening face nor the tent slowly rising in his jeans.

He shifted again, forcing his eyes up to the ceiling. He struggled to focus on what his teacher was saying, but all he could hear through the blood rushing through his ears was the utterance of "triangle," which did the very opposite of helping his…current condition.

Dipper bit his bottom lip hard, but not hard enough to draw blood, and sighed shakily through his nose.

You can do this, Dipper. You can do this. Thirty minutes left.

Dipper was unable to force his shoulders to relax. Feeling all his resolve crumble, he glanced down at his book again.

Three lines connected point to point to point stared back at him.

Mocking him. Seducing him.

Dipper peered around nervously again and making sure everyone was still ignoring him, picked his hand up and with a trembling hand, placed the pad of his finger on the point labeled A.

Dipper swallowed the moan bubbling in his chest. He gulped thickly, his other hand falling to his lap and he gasped softly at the feel of his erection pressed up against his hand through his jeans.

His eyes darted back up and Dipper nearly shrieked when he saw one of his peers shift in her seat. She didn't turn around to look at him, however, and just leaned her cheek against her hand boredly.

Dipper shook his head in relief and, very slowly, gripped his erection through his jeans, sliding his hand down. Dipper chewed on his bottom lip and returned his eyes back to his notes, paranoia gnawing in the back of his mind.

The uncertainty in his gut calmed as his sight was stolen by the triangle in his book, anxiety burning away at the wake of the growing inferno inside him.

Dipper mindlessly slid his hand back up his clothed cock as he dragged his finger from point A to B.

Dipper parted his lips, panting softly. The buzz of the air conditioner drowned out Dipper's small noises and the teen's hand on his crotch sped up as he dragged his finger from point B to point C.

He pumped himself harder and choked a little on the saliva bubbling up in the back of his throat. Without a single glance up to make sure no one was watching him, Dipper buried his face into his book, kissing the triangle wetly and huffing breathlessly as the heat in his stomach finally released.

Dipper let go of his softened cock, bracing his hand against his chair instead. His breath came in sharp pants through his nose. He laid on his book, limp, senses slowly trickling back into him.

Dipper glanced up through his bangs and nearly fell out of his seat at the sight of the girl in front of him staring at him with huge, suspicious and confounded eyes.

"Hey! Turn around!" Dipper snapped her in a breathless whisper-yell.

The girl looked taken aback by the croak of the brunet's voice. She shook her head, repulsed, and turned back around to focus her attention on the board.

Dipper sighed, moving to sit back up. Humiliation and horror swelled in his heart and right then and there, Dipper swore he could've melted right into the floor.

Oh god. Oh god. Oh fucking god.

Dipper rubbed his still red face with his perspiring hands. He tried to glare down at the simple little shape in his book, only for the hard look to fall apart completely.

God. What was wrong with him?

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Welp I hope you guys enjoyed whatever the fuck that was. This is def not my best writing but well. It's about literal triangle fucking I think I get a pass.
This is gonna be a drabble series set in the same universe so don't expect chapters to really directly connect to one another okay.

Anyways, thanks for reading! Please review if you enjoyed!