The Mercy Sisters were psychotic twins by the name of
Grace and
Mary, they resided in Long Island, New York with their parents, who eventually became their first victims. The twisted sisters continued their sociopathic behavior by killing anyone that upset them. They stashed the bodies of most of their unsuspecting victims in the barn of their family's Southampton summer residence. Their madness resulted in a substantial reward being offered for their arrest, gaining the attention of the mercenary
Deadpool (Wade Wilson) who presumably took Grace's live after she had euthanized Mary to relieve her of her suffering.