This is a cross-over between "Gravity Falls" and "Steven Universe." All characters belong to Alex Hirsch and Rebecca Sugar, not me.

Gravity Universe

The Crystal Gems transported onto a platform surrounded by thick woods.

"Spread out and keep your eyes open," said Garnet, the tall and taciturn leader with an Afro hairstyle and mirror shades over her three eyes.

"What are we looking for, again?" asked young Steven Universe, the youngest member of the Crystal Gems whose gem powers were still unreliable. Even so, his pluckiness and creativity had proven useful time after time.

"Thirty years ago, we detected a powerful energy spike in this part of the world," said Pearl, the pale and willowy member of the Crystal Gems. She had a sharp nose and a white crystal on her forehead. Her intelligence and grace in battle were extraordinary, although she could get flustered easily. "According to my measurements it was unlike any of our normal sources. We couldn't pinpoint a location then, but recently the spike happened again and the energy flow has persisted, so that we could trace it here."

"Chill, you guys," said Amethyst, the BBW group member with long, flowing purple hair. She tended to be the wild one of the bunch. "These woods look sweet to explore. Let's have fun while we do this."

"I'm with you, Amethyst," said Steven.

"Steven, stick close to her," said Garnet. "This could get dangerous."

"And fun," said Amethyst.

"So what do you guys think is going on?" asked Steven.

"Hybrid technology, perhaps," said Pearl. "A renegade Gem, turned monster, may have illegally shared our technology with humans."

"Isn't sharing a good thing?" asked Steven.

"Our laws say no unnecessary contact with humans," said Garnet.

"I break that by wrestling as the Purple Puma," said Amethyst. "But hey, rules are made to be broken."

"Our ancient structures have built-in wards that turn humans away without them even realizing it, for their own safety," said Pearl. "Remember how the Pizza family said they had never been to our part of the beach, even though it's a small island? They couldn't have come there at all without an invitation from you, Steven."

Steven looked upset, "B-but, what about my Mom? Was her loving my dad illegal? Am I... an unnecessary contact?"

"What Rose did was... unique," said Pearl. "But..."

"The two of you were really pissed when she started dating Greg," Amethyst said. "I was cool with it."

"But now that you're here, we accept you, of course," said Pearl hastily.

"That's creepy," said Steven. "You guys came here from space, put up buildings and had wars all over the place, and you never talked with the people who really belong on this planet? My Mom did the right thing, reaching out to people, and you said it was wrong."

"Steven, you are too young to understand our ways," said Garnet.

"You're right, I don't and maybe I don't want to," said Steven. "Leave me alone! I have to think."

He ran off into the woods. The others were about to follow, when dozens of bull-headed men came out of the woods and surrounded them.

"We Manotaurs don't like it when females pester a boy-child," said the leader. "Attack them!"

Amethyst drew her whip from her gem, Pearl drew her spear from hers, and Garnet activated her power gauntlets.

"I don't detect any gems," said Garnet.

"So they're either rare native fauna or monster-spawn," said Pearl.

Amethyst grinned and said, "Just what we needed, a little combat to work off our frustrations. You boys just bit off more that you could chew."

Steven ran until he found a road. He followed it to a two-story, run-down wooden building with a sign on top reading "Mystery Shack."

Two kids about his age were playing in the yard, throwing a spinning disk back and forth.

"Hi!" Steven called out. "I'm Steven Universe. Want to be friends?"

"Sure!" said the girl. "I'm Mabel."

"I'm Dipper," said the boy. "Are you a tourist? Where are your folks?"

"I'm with the Crystal Gems," said Steven. "At least, I thought I was but I'm not sure I really belong."

"Is that a band?" asked Mabel. "It sounds like one."

"We have a band," said Steven. "Steven and the Crystal Gems. I play guitar and sing."

"Cool!" said Mabel. "A boy rock star. If you were a little older..."

"Are you guys going to give a concert around here?" asked Dipper

"I wish, but we're here on a mission," said Steven. "We investigate mysteries and save the world from monsters."

"How about that?" said Mabel. "So do we!"

"Really?" said Steven. "You've seen monsters around here? Maybe you could help us."

"Yeah, big time," said Mabel. "Gnomes, vampires, zombies, you name it."

"Mabel, I'm not sure we should talk about this with outsiders," said Dipper.

"You're just like the Crystal Gems," said Steven. "If nobody talks to anybody, how are we going to team up and beat the monsters?"

"All right, I'll give you a chance," said Dipper. "If you want to know about monsters in Gravity Falls, you've come to the right place."