Twins of light and dark

Brand new day!

"WAKEY WAKEY, YOU TWO!" Stanley Pines yelled as he opened the door, the twins still buried under the covers, both siblings not wanting to wake up.
At least not now, anyway.
"Dipper? Mabel?" he called, a little quieter.
"Staaaaaan, it's way too early!" Mabel whined, opening her eyes but making sure her wings were covered by the pink duvet.
Dipper on the other hand was still trying to sleep.
"Well, you guys have 10 minutes! tourists are coming in early! chop chop!" Stan barked before closing the door and going to the gift shop.

Dipper Pines groaned, opening his crimson eyes and trying to adjust to the brightness of the room. He got up and started to get ready, in his 'normal summer' clothing rather than the formal outfit he had worn the previous evening.
When he was done, he straightened his pine tree hat and put in some green contacts, retracting his fangs.
"Hey, you got any more of those?" Mabel asked, brushing her hair which was now absent of the pink streaks, her shooting star sweater hiding her wings.
"Yup. I always have a spare" Dipper replied, handing Mabel the spare case of contacts. She giggled, putting the contact lenses into her neon green eyes, the lenses making them the same shade of green as Dipper's.
"Come on, let's get down there" Dipper urged Mabel, running downstairs. Mabel sighed and followed behind her brother, willing her wings not to flutter.

Time dragged on as the twins worked, Stan greeting the tourists and taking them on a tour through the shack; thankfully neither Mabel nor Dipper were being used as attractions.
Dipper looked up from sweeping the floor to see Mabel working the cash register and talking to the customers, making him smile.
His eyes then widened in shock as he saw a pink streak slowly appear in Mabel's brown hair, a few more appearing soon after.
Mabel was unaware of this, noticing a few looks given to her by the customers. She gulped and served the last of them before they left.
"Bro-bro? I got a few weird looks. What's going on?" she asked, her voice wavering slightly.
Dipper dropped the broom as if it were on fire, running to her and standing next to her in front of the mirror, only Mabel's reflection showing up in the glass.
Mabel gasped, seeing her skin was glittering, gold around her eyes like eye-shadow, her hair almost entirely pink with a few streaks of brown hair.
"No wonder they were looking at me weird!" she breathed, the gasped, seeing Dipper's skin had turned deathly pale and his hair was black as midnight.
"What do we do? we need to hide somewhere!" Dipper said worriedly.
Mabel thought for a moment, then smiled, her eyes wide.
"There's a cave in the forest! I found it when I was outside on one of my breaks here, it's perfect! there's more small fairies as well as a few bats in here. We can stay there!" she exclaimed excitedly.
"A cave? are you sure that's going to hide us?" Dipper asked, still a little sceptical.
"I'm sure! come on! before Stan and Ford catch us!" with that, she flew out the open window.
Dipper hissed in pain as a ray of sunlight touched his hand, grabbing a black umbrella and going outside, opening it before running after his twin towards the cave.