#AtoZchallenge —P is for —Pentos

From the Shores of Dragonstone to the frozen lands beyond the Wall comes the 10th anniversary of the AtoZ challenge...

Game of Thrones source: Wiki

Warning; there may be spoilers

Pentos in a Game of Thrones is one of the Free Cities in Essos located across the sea from the seven kingdoms of Westeros. HBO filmed on location in Malta. I would love to visit Malta. Pentos is where Dani and Viserys live AND where Tyrion sails to as a stowaway in a crate. He had just killed his father Lord Tywin Lannister and was helped by Lord Varys sail away on a ship to Pentos.

Can you guess who the letter is?

P is a Grand Maester of the Citadel who has served in King's Landing and on the small council for over forty years.