Mekritus guards the hideout of the Sanguinesti Order of the Myreque. He can be found in the bedroom of the barracks, where the Myreque members sleep. Unlike most of the Myreque, he is not particularly involved with any quests, though the player can get information from him about the kind of weapon that would be useful for killing the Vyrewatch in Legacy of Seergaze. He will tell the player that a flail would be a good idea, giving you the idea for the Ivandis Flail.
During The Lord of Vampyrium, Mekritus A'hara assists in an attempt to kill Lowerniel Drakan, taking on the guise of "Mekky Graah" as a vyrewatch disguise. Once inside Castle Drakan, however, he begins to battle against Drakan's venator in an attempt to escape an ambush. He is ultimately killed when a venator smashes through a window and throws Mekritus A'hara out of it. He used a blisterwood sickle during the assault.
During River of Blood, his severed head is seen on a bookshelf while the player is hallucinating. He refers to how much his head hurts while it is severed.
In In Memory of the Myreque, a statue is built in his honour. It is revealed that he used to be fretting about one thing or another, and the only thing that ever calmed him were Mort myre pears, as they have medicinal properties that quelled his nerves for a time.