I'm seconding that the quills we see in the Bedrock were for writing contracts, and a simple assumption is that the Peacock's grandfather used to work on contracts with the hotel (probably left a passport, too, since writing wise it makes sense to cash one of those Chekhov's guns here quickly since we've got 3 more that could come up). Obviously there's some magic/supernatural bits at play with linking his dreams to the place these quills are, maybe they've been used for contacts for so long that they're starting to become an artifact, and are calling out to his grandson.
The tie there to Argos is very interesting, though! If we want a crazier theory, the magic of the quills and peacocks in general can be used for spying on locations they're left behind at - fitting with the eye on the feather, no? We don't know how Argos interacted with Clement or Jean really, did he ever care to interfere with what we're subverting the Bedrock into? Or would he maybe care to now that there is a very crafty new master (if you play that way, of course)? I don't know how Argos can interact with the guests, but could he have subverted the peacock grandfather to be a mole? Or maybe this hints that the upcoming peacock guest could be one? Impossible to know until we know who he his and if he'd let himself get swayed by Argos... And of course, the two may not have any tie at all, but where's the fun in that in the theory thread!