Merion was a maester of the Citadel.
He was made Grand Maester at the age of sixty-six and sent to serve the court of King Aegon V Targaryen in King's Landing to succeed Grand Maester Ellendor. He died on his way to King's Landing and was succeeded by Grand Maester Pycelle.
His work The Red Dragon and the Black was left unfinished.
He once referred to the custom of Lys, Myr, and Tyrosh to grant licenses on ships to prey upon those of their foes as "piracy with a wax seal".