The saddest AU I've come across so far. Just... just let me cry here for a second. ;-;
Creator: Inumaru12
Basic Storyline: Mr. and Mrs. Pines were expecting twins, but when they were born into the world, the female, Mabel, was stillborn. Dipper grew up alone and rejected by his devastated parents.. When his parents send him to Gravity Falls, he gets to know the teenagers and neighborhood kids really well, a lot of them acting like family to him. Even Robbie.
There's more of the story about Bill making a deal with Dipper, but that is huge spoilers, and probably the biggest emotional hit, so I won't type/add it in here.
That's the general idea... *sniff*
Characters:
Dipper is a sad little bean who just needs attention and love for once in his life, and when he goes to Gravity Falls, he gets just that. He sometimes has dreams of his lost sister, except she's always facing away from him and is out-of-reach.
Mabel is dead.
Grunkle, at first, was hard on Dipper, but realized he needed love. He actually forces the Pines parents to let him have Dipper every summer because he realized how much love Dipper really needs.
Gideon still wants to get the shack, and befriends Dipper when he arrives at Gravity Falls to use him, but later warms up to Dipper and feels a little bad about his plan. He goes through the plan, however, but later gets a redemption arc.
Soos is the same cuddly, friendly character we know and love, except he's even MORE caring, and is like a big brother to Dipper.
Lee, the blonde-haired teenager, is probably the most brotherly person to Dipper after Soos.
All of the other characters are mostly the same/aren't mentioned.
Here's some tissues if you need them...