The bus was coming today.

It was the twins' birthday. They would be thirteen tomorrow.

Today, they were supposed to leave.

Mabel had spent the night having one last slumber party with Candy and Grenda, who had seen her off this morning with hugs and sobs and promises to call and write.

Dipper had no one in Gravity Falls to say goodbye to, not really.

As the twins and Stan stood near the edge of town waiting for the bus, Stan noticed how Dipper was trying to hide his tears, blinking a lot and lowering his gaze.

Mabel couldn't be bothered, and her tears were flowing hot and fast over her cheeks as she stood silently, holding onto her pile of luggage to keep it upright.

If only they had more time, another week, month, year. If only the bus never came, and they never had to face it.

But the bus did come. It pulled to a stop at the curb, and the doors hissed open.

Mabel hefted her bags up onto the steps, but then she turned back.

She raced towards Stan and slammed him into a hug, her crying turning into the ugly kind with snot bubbling from her nose as she tried to choke out a goodbye.

"G-grunkle Stan, I'm gonna come back next summer, and I'm gonna call every day, okay? So this isn't goodbye for real."

"I know, kid," Stan said, the sadness he felt slipping into his voice.

"Take care of Waddles for me?" she squeaked. Stan knelt to fit into her hug better, and patted her on the back.

"Of course, sweetie."

With a sob, Mabel broke apart from her Great-Uncle and turned to her brother.

In an instant, Dipper felt his sister's strong grip around him, catching him in a hug that practically choked him. He stopped trying to hold back his tears, and they rushed into Mabel's hair.

Mabel was crying too hard to talk for a moment, until the bus driver honked and jolted her out of it.

"What I said to Stan goes for you too, okay?" Mabel said, her voice thick with a sadness that none of them were used to hearing.

"This isn't goodbye for good."

"I know," Dipper said, giving her a sad smile. He couldn't break down the way she was, not yet. Mabel had to go back, had to be able to get home without worrying any more than she already was. He couldn't stop her from that.

Mabel leaned into another hug, and whispered in Dipper's ear.

"I love you, bro-bro."

"I love you, too," he whispered back.

And then the bus driver honked again, too soon, and Mabel was pulling away and pulling out her bus ticket, and all of this was happening too soon, and now the bus doors were shutting behind her and it wasn't supposed to be this way!

The bus began to drive off ever so slowly, working its way up as it drove towards the edge of town. Dipper and Stan could see Mabel out the back window, waving, and Stan began waving back.

Dipper started to run, chasing after the bus, heading for the edge of town. Maybe, this time, it would be different, maybe he could do it this time.

He had to try.

Mabel could see him running, and she'd started crying even harder, because she knew he wanted to come home with her, and this summer wasn't supposed to turn out like this.

The bus rushed past the sign that marked the edge of town, back towards Piedmont. Mabel, still out the back window, watched as Dipper kept chasing the bus.

Watched as he hit an invisible wall and stopped.

Dipper pounded his hands against the wall and screamed. Why him, why was he the only one who could feel this invisible dome over the town of Gravity Falls, why was he the only one trapped inside it?

He threw himself against the barrier, hoping that maybe this time, or this time, he'd be able to break through, able to go back home with Mabel.

Stan rounded the corner to find Dipper lying on the ground, sobbing, at the edge of the town, the very barrier of where he could go, of where he'd live his life.

"Hey kid, hey, it's gonna be okay," Stan said, leaning down and laying a hand around Dipper's shoulders. "You heard her, she's gonna be coming back."

"I know," Dipper sobbed.

"But I miss her so much already."