*In this AU, the monsters from Undertale end up in Gravity Falls. They settle there, and Dipper and Mabel meet them when they arrive the next summer. At this point in time, it is 2016, the two have known each other for three years and are 16 years old, and Frisk is a girl.*
Frisk's POV
As Frisk was getting ready for her date with Dipper, she could not be more excited. When she first met him, he seemed like a normal kid. But after getting to know him, she loved how smart, mysterious, and cool he was. Every year she awaited the day he would come back, and she would dread the day he left. She had not changed much since she left the Underground, except that she had decided to grow out her hair. She hated it when people had asked what gender she was, so she thought that this was a good defining characteristic.
When Dipper came back to Gravity Falls this year, he had immediately asked her out on a date, and Frisk felt so good, so happy, that... she had fainted. She felt so stupid, but Mabel, Dipper's sister and Frisk's best human friend, had told her that Dipper thought it was the cutest thing ever.
Frisk eventually settled on what to wear, going with a purple skirt and her usual sweater. She tied her hair back in a ponytail, and went to go tell Toriel that she was leaving.
As she left her room, she saw Papyrus in the kitchen, with Mabel sitting at the counter. When Mabel saw Frisk she gasped and her eyes got big.
"Frisk, you look adorable!" Mabel told her. "Oh my gosh, Dipper's going to love this look!"
"Y-you really think so?" Frisk said, getting a little embarrassed by what Mabel was saying.
"Indeed, my dear Frisk! You look like one of my finest plates of spaghetti!" Papyrus said, looking away from his cooking.
Frisk giggled a little. "Thanks, Papyrus. Coming from you, that's alot."
She then walked over to the living room where Toriel was reading on the couch. "Mom, I'm going on my date now!" Frisk called, and then she began walking out the door.
"Hold on, Frisk," Toriel stopped her before she went outside. "You know the rules, right?"
"Be home by ten, don't talk to strangers, say please and thank you, don't do... y'know, that, and when I get back, tell you every detail."
"You go have fun then! I'm sure Sans will finish up getting Dipper ready soon. I love you, my sweet child!" Toriel called out to Frisk.
"Love you too, Mom," Frisk told her as she walked out the door.
Dipper's POV
"Hey, Sans, do you think that I should go with pants or shorts?" Dipper asked the skeleton.
"Well, I don't think shorts would be the best idea," Sans told him.
"How, come?" Dipper asked.
"Cause I'm the only short one here!" Sans said, delivering the punch line.
Dipper began to laugh. When the monsters first came, he shared a similar disliking for Sans' jokes with Papyrus. But now, they were pretty humerus! (He had told this to Sans twice now.)
"No, but seriously, kid. It's way too cold. Man, it must be nice to have practically year-long sun in Piedmont, right?" Sans asked Dipper.
"Eh, I guess. You get tired of all the fog, though. It's all along the San Francisco Bay, and the southern California coast. But do you know what happens when the fog clears in California?" Dipper asked as he finished getting ready, setting up for his own joke.
"Nope. I've never been. What happens?" Sans told him, seeing where this was going.
"UCLA!" Dipper told him. The two began to crack up.
"Hehe, alright, kid, ya look good. Since Frisk is my 'daughter', and since Stanford and Stanley are your guardians, let's go over the rules with them, OK?" Sans told him, going into father mode.
After about twenty minutes of going over some things that he already knew, he was off.
*After 1 hour at dinner, the two make their way to walk along Lake Gravity Falls.*
Frisk's POV
"-So my Great Uncles switched clothes in, oh, I dunno maybe five minutes, and just as Bill is about to kill Mabel, my Grunkle Stan, who Bill thinks is Ford, erases his own memory to erase him!" Dipper tells her, finishing his story. "It had to be the craziest day of my life."
"Huh, sounds like some of the stuff I did in the Underground. I watched my friends die, like, five times. I hated it, but none of them really had the connection that a sibling would have, let alone a twin. I guess Sans had that feeling when Chara killed Papyrus," Frisk told him, shuddering when she said it.
They were about to head home after they made it around the lake once, and Frisk decided she wanted to say something. "Thank you, Dipper. I really enjoyed tonight. Do you think maybe..."
"Next week? Same time?" Dipper said, completing her thought.
"Yeah. Yeah, I'd like that," Frisk said, drawing closer to him. Just as they were about to kiss, something interrupted them.
"Paps, stop! You're using the camera wrong!" Someone whisper-shouted in the bushes.
"Wait... Mabel? What are you and Papyrus doing here?" Dipper asked.
"Oh, nothing... Just documenting your entire date in pictures," his twin answered him.
Frisk began to laugh at this. Dipper chuckled a little, too.
"Oh, that's so YOU, Mabel. Really a class act," Frisk told her.
"Well, thanks. I guess we don't need to document this part. Come on, Papyrus," Mabel told her friend.
"But I wanted to see what love is like!" Papyrus complained. Mabel sighed, then walked over and kissed the skeleton.
"There, better?" Mabel told him, and then walked away, with Papyrus' jaw hanging open. As Papyrus passed out from shock, Dipper and Frisk began to laugh. They then looked each other right in the eye, and kissed. Frisk felt not just determination to be with Dipper forever, but... Passion, too. And they both felt the happiest they've ever been.
Note: Thank you for reading, guys! I may or may not come out with a backstory, with an adventure happening, and there is an even slimmer chance of me coming out with a lemon to go with this. Anyways, Ciao!
WatamelonACE