I doubt the fairies have one laying around.
Do you know (or remember) what was used before ballpoint pens?
Yanking one out of Pavauris' plumage is ill advised - while he's paying attention.
Stealing one when he's asleep, however...
Read the signpost to find out!
Only because you deemed it so - if the water is still flowing, return to the gallery and take the colour stone off of the basin.
Otherwise, see if you can figure out when the 'hour around midnight' is during summer.
Asking the peacock directly reveals that the sun rises in the west during winter.
That means it must set in the east - but remember, he sleeps around midnight.
Place the goblet of honey on the stone that represents the south; you'll see Pavauris settle down to sleep soon after.
You can take a feather, easy-peasy. Brush acquired!