Dipper Pine's Prophecy

Dipper Pines didn't think that this summer would be any different than every other summer since he was twelve. He would return to Gravity Falls, spend quality time with friends and his Grunkles, Mabel would obsess over her ideal of summer romances, their Grunkles would tell them about their death defying adventures aboard the Stan o' War, and Dipper would continue his paranormal investigations in his journals. Still exiting, but somewhat predictable. What he didn't expect was for his Great Uncle Ford to bring him an ancient tablet for him to translate as a gift, he especially didn't expect a handsome blonde to pop out of nowhere and pull Dipper into his own summer romance.
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Or where Dipper is unaware that he is the subject of an ancient prophecy which puts him in sight of many powerful beings who want a piece of his destiny. One of these beings being Bill Cipher, who is determined to make Dipper his property, and the best way to do achieve that goal, he decides, is to first take advantage of one of the human's major flaws. His heart.