so this is based off of the gravity falls 'Lost Legends' book by Alex Hirsch, story three 'Don't Dimension It', where you are apart of the Mabel-verse. JUST A BIT OF CONTEXT HAVE FUN

Mabel falls through dimensions after being pulled into a wormhole in accident while out with Dipper, Ford, and Stan to try to patch for multidimensional rips from weirdmageddon. Still falling, and eventually landing on solid ground, only to look up and see a dimension of more Mabel's! Probably thousands!

Mabel: "What the hey-hey?! Where am I?"

She gets up and starts to wander, it wasn't much, flat pink ground with the thousands of Mabels all around her.

Mabel: "Razzle my dazzle, it's a Mabel Bonanza! There's every possible version of me!"

looking around, the points out some of the Mabel's

"Table Mabel.. Molecularly Unstable Mabel.. Teeth Mabel?! girl you are fierce and I love it!"

after looking around and getting checked in as slightly arrogant Mabel, she learns about MAB-3L, and how she's stuck, she tries to find other Mabel's to help her get out and back home, running around she bumps into you!

Mabel:"ACK-!

both of you falling over onto the ground, she gets up and quickly offers you a hand, frantically apologising

Mabel: "OMG! I'm so sorry! I wasn't looking where I was running! Sorry! Which Mabel are you?"