Poor Grunkle Stan…the FBI is gonna confiscate all his issues of "Fully Clothed Women".

Take a look at that wheel with Bill we've seen in the opening credits:

In addition to the common theory that each of the symbols on the circle represent a resident of Gravity Falls, there was another theory that the order of the symbols is based on what order characters make a pact with Bill.

First, we've seen Little Gideon (The Pentagram Star) make a deal with Bill to steal information from Grunkle Stan's brain.

Next we've seen Dipper (The Pine Tree) make a deal with Bill to recover information from the laptop. Notice that the Pine Tree is directly after the Pentagram Star.

What comes after the Pentagram and the Tree? The odd crescent-moon shape, most likely corresponding to Grunkle Stan.

If the theory's true, Grunkle Stan is due to make a bargain with Bill. And judging by the preview, Stan looks like he's going to be between a rock and a hard place next episode, which would be perfect ground for Bill to manipulate Stan into a fiery blue handshake. And judging by the apocalyptic imagery at the end of "Northwest Mansion Mystery," this dark bargain won't end well.