Editing The Chasm

Towards the northern edge of Port Blackheart there is a natural rift in the earth about 300 metres across.  It descends deep into the earth and there is no record of anyone having traversed it's steep sides to find out what was at the bottom.  When it became known that Port Blackheart was a pirate port, a place where any beast can exist without fear of persecution (or not, at least, because of what it was) the demons and the devils came.  It soon became apparent that such beings of absolute evil could not exist with the rest of the community.  After a short time the devils and demons agreed to relocate to the chasm where they serve a vital function, protecting the city of the creatures that sometimes emerge from it's depths.

There is a fierce rivalry between the demons and devils.  Each occupies there own side of the chasm and they refues to venture into the other side or even acknowledge the existence of the other faction.  A simmering hatred and potential violence exists between them that occasionally erupts in small bloody skirmishes but the leaders of both factions soon quell these.  Port Blackheart is a valuable resource to both sides, a chance to keep their eye on mortal affairs without complex subversive work.  Neither side can afford to lose the opportunity to stay there and so a tense peace is mostly maintained.

Many have speculated why the devils and demons are content to remain such good citizens and there are therioes and suppositions from all angles about their eventual aims.  Nobody knows for sure what they hope to achieve from their time in the city but those who claim they provide a valuable service and expect nothing in return but to exist are clearly delusional.