Aaron Slaughter was a Black Mask monster hunter of the House of Slaughter under the Order of St. George and Erica's superior and adoptive brother. Inducted into the organization following his orphaning in a car accident, Aaron would become bound to the owl totem Hootie and trained under Jessica Slaughter as a Black Mask. While initially alone, he would later be joined by Erica Slaughter, who became his adoptive sister. A young Aaron would become romantically involved with Jace Boucher, who had posed as a new transfer to the White Masks and was made his roommate due to a lack of space. After Jace attempted a coup of the House of Slaughter, Aaron fought against him, losing his fingers which had to be surgically re-attached. His defeat of Jace's monsters, however, would earn him his teeth as a hunter. He continued to train until reaching the status of a full Black Mask, and would work as Erica's superior from a position inside the House, rather than out in the field. Aaron would be tasked with killing Jace Boucher, but upon discovering his sanctuary for victims of monsters, he helped him fake his death by cutting off his hand and delivering it to the Old Dragon, leaving Hootie with him. Shortly after this, Aaron would be sent into the field after Erica broke the Order's rules by allowing a civilian to see monsters. While he attempted to kill Tommy Mahoney, he was stopped by Erica and convinced to defend the town of Archer's Peak. While buying Erica time to find the children the mosnters were after, Aaron was killed by a pack of Oscuratype adolescents.