Blacksite Border Patrole

To enforce regulations, control the population and collect trading taxes, but also to ensure that the settlements are safe from wandering predators, the Border Captainmakes use of his own military unit, the Blacksite Border Patrole.
Military and Police Syreni who went black often end up in this unit where they get paid well and have a lot of room to move and act on their own volition.
Because in the City of Aogua these positions are often filled by the Syreni Selachimorpha (sharks), the Blacksite Border Control also consists mostly of them and with them they bring their protocols and training which makes the Blacksite Border Control nearly indistinguishable from other military and police units in the city. Even paperwork is still a thing as to not let things get too much out of control and incite a riot amongst the Blacksite residents.
They can be divided into officers along the border, making sure that no one goes through without permission while patroling the edges of the Blacksite in a Biocle (a semi-sentient species affected by Deep-Sea Gigantism and used as vehicles or living spaces), officers who protect and patrol the towers and officers who roam through the Blacksite, never entering settlements but patroling around them for protection or go on hunting trips for bigger predators. 

They all share the same name, training and Captain and residents don't see them differently from each other, no matter if they are part of a unit that is protecting them or part of a unit that is charging them. The relationship between the Blacksite Border Patrol and the residents is strained to say the least and with every greedy move from the officers, the animosity grows with active Anti-Border groups already active and out there looking for opportunities to shift the balance of power.