I expect fut coins he'll tell Bigby just how deep this rabbit hole goes, explain why Fabletown needs him more than they need the obviously inept home office, and so on and so forth.
Maybe Bigby will get his man, or maybe he'll discover that there are forces out there too strong even for him--which will only be acceptable if the finale closes with Colin turning to a beaten down Bigby and saying, "Forget it Bigby, it's Fabletown." Probably not, though.