The first time Dipper sees a monster, it's hiding in the very back of a closet full of toys and clothes. Mabel fashions them curtain capes and flashlight swords, and they charge, weapons raised.

The monster disappears soon after ("Silly goose," Mabel says), and they gorge on celebratory buckets of popcorn and plan for impending dust bunny invasions, never realizing that their escapade becomes cause for concern. (Their parents talk in whispers - has it started? and I don't know.)

But then again, every hero starts off young and small.

The Pines grow up riding bicycles around the cul-de-sac, jumping on trampolines, and eating ice cream in the park. The only hand to hand combat training they receive is two weeks of trial tae kwon do lessons and years of video games, and the only demigods they know are straight out of books and movies.

Myths - Greek or Roman or Egyptian or otherwise - are elaborate stories devised to explain the natural order of things, and nothing more.

One day, their parents tell them they're going to spend their summer with their Great-Uncle Stan, all the way out in Gravity Falls. They fill up their suitcases, thinking aloud about the friends they're leaving behind and the people that they'll meet.

They don't realize they're just trading some monsters for others, no, not yet.

It's dark and they're outside, roasting marshmallows around a campfire when they hear a roar and a cry for help. They run, gooey sticks still in hand, and pelt the great hulking beast about to pounce on a young girl, throwing chocolate and graham crackers and whatever else they can find. The sweets and rocks and cans bounce off the creature's skin, but it's just enough of a distraction to allow a group of warriors to embed arrows deep into its flesh.

After the monster disintegrates, Dipper just stands there, tongue-tied, wondering if he could possibly feel more intimidated by the sudden appearance of these girls with their weapons aimed right at him.

Mabel, though, ever unafraid, simply walks straight up to them to ask if she can trade her grappling hook for her very own bow.

Their leader laughs. "We'll see." But then her face turns dark, bright blue eyes suddenly serious. "My name is Thalia," she begins, "and according to the oracle, you and your brother need to come with me."

They move around the Mystery Shack in silence, packing just enough for their long journey to the opposite coast. Wendy gives Mabel her hat and Dipper his favorite postcard from the gift shop, and Soos makes them promise to trust their instincts. "From one dude to another, us campers need to stick together, alright?"

Grunkle Stan sighs. He takes down the framed picture they drew of Duck-tective and opens the safe hidden just behind. He tosses them each two bags of heavy coins, reminding them to remember all the tricks he's taught them. The thick envelope is last. "This," he says, "will help you on your travels. They're recommendation letters, passed down from generation to generation. Proof that we're a special kind of family."

Mabel is the first to give him a hug, and Dipper joins soon after, and it's only when Thalia tells them they need to get going that they break apart.

They clutch at their belongings, drachma and denarii and references and all, and wonder if this is the last time they'll see Gravity Falls. They gaze out the windows of the car, hands pressed against the glass as they yell their final goodbyes.

"Ready to save the world?" Dipper asks.
"We don't have any choice but to be," Mabel says.

She raises her hand and he meets it.

Later, when they're telling their story, their very own epic, they'll say they began their quest with the best high five in recent history, and there will be few that disagree.