The Erinyes or the Furies are supernatural entities that seek to punish those that have escaped justice.
The Erinyes had attached themselves to Hellboy's soul. Two souls of doctors brought Hellboy to Dr. Hofferman to cure him. Dr. Hofferman summoned the Furies to demand why they have haunted Hellboy. It was revealed Hellboy's half sister Gamori had summoned them to punish them for Hellboy's part in murder his family. However the Furies determined that Hellboy was innocent and turned their anger to Gamori for lying to them. Before they took her away, Hellboy asked what would happen to her. The Furies declared that Gamori would suffer at their hands, once they deemed she was punished she would be freed, left to wander to the abandon city of Pandemonium where she will witness Satan's corpse. She will scream in horror, her screaming will cause the city to crumble and shatter. Once Pandemonium falls the fire in Hell would be snuff and will be the end.