Demonic Symbols||Gravity Falls AU

(NOTE; I'M REWRITING THIS FIC
Not much is gonna change except the plot is gonna make more sense and it's gonna be better written (i hope). I'm not discontinuing or deleting; just rewriting!)
(DISCLAIMER; I DO NOT OWN GRAVITY FALLS)
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Five years ago, in the quaint town of Gravity Falls, a catastrophe occurred like no one had ever seen, and it's never been talked about again by any of the citizens. Because of the events from that unmentionable cataclysm, the people in the town were forever affected and the status quo was all but shattered. The town stayed standing, though. It's resilient. It can survive anything. Or so they think...

Five years have passed since their first trip to Gravity Falls, and Mabel and Dipper are now graduating from high school. This summer was going to be their last trip to Gravity Falls. They got accepted into the towns' community college (who knew they had one) so they decided to stay at the Mystery Shack full time. Sure, there were better schools the two could've gone to, but they wanted to go to Gravity Falls. The town was their rightful home. It's the place they truly belonged.

Five years have passed, and tons of things have changed; about the town, about the twins. A lot has changed, and a lot is going to continue to change. How the town will handle it, is the question. But all Mabel and Dipper really know anymore, is that they'll fight tooth and nail for their town no matter the threat.