Arrogant, self-interested and self-motivated. Mercer awoke with a detachment from the world and an interest in death. He quickly took to studying places rich with death and decay--Ascalon and Orr with particular interest, and on one particular trip, found an old tome from an ancient necromancer which he used to sharpen his skills. 

Upon return from one such trip, he met Talæesyn, a newly awakened and bright-eyed sapling, whom he promptly decided to court. They traveled together to Ascalon for a year so that Mercer could continue his research on the Foefire and the ghosts. Though Mercer would never admit it, and it would take a long time for Talæesyn to say it, their relationship exhibited an unhealthy amount of control and power-imbalance, and after two years, they broke up. 

During Heart of Thorns, after Shylah runs Talæesyn through on her blade, Mercer becomes enraged. After patching him up as best as he can, he follows Shylah into Brisban Wildlands, embracing the power of Mordremoth in an attempt to kill her. Instead, he winds up losing all sense of self and is killed by ______.