He'd broken his promise.
When they had first met, Bill had promised he'd never leave her behind. At first it was just to gain her as an ally, but over time he'd come to think of her as a little sister.
Did it apply to if she left him behind?
"October! I'm sorry, okay?"
"If you went back to hibernating, I won't talk to you when you wake up."
Still silence. He reached out with his mind to her, finding nothing.
Even if she was asleep or blocking him he would've found something.
She was out of range.
"October!" This wasn't good. "October Gravity Oaks, come out right now, or you're in big trouble!"
Usually, he would've heard a snappy reply telling him he wasn't her father. But there was nothing.
This. Was not. Good.
October pretended to be an independent, anti-social, mature being, but when push came to shove she was just a scared little kid deep down. The same October she'd been when she left Boston, Massachutses alone in 1710. The same October she'd been when she found Gravity Falls, her precious paradise, in 1712.
She hadn't changed one bit in 300 years, which could be a good thing or a bad thing. When she was lost in the forest . . . it could be a bad thing.
Even though there was nothing towards the edges of the forest that could harm ghosts, there was bound to be some sort of trouble in the middle.
And if anything happened to Bill's first friend since he-didn't-even-remember-when, he'd never forgive himself.