Payment
After talking to the manager, William, Del, and his associates quickly left that place, heading towards the place where their ship was docked.
Del wanted to bring in his 'products' as soon as possible so he could receive the spiritual crystals involved in this business.
And as for why he was selling these slaves directly to the Black Market, it was because that way he could get his hands on the crystals in less time.
Like pirates, Del's group didn't have much patience or great intelligence to maximize profits by selling slaves directly at auction. Because of this, it was common for people like them to pass this service on to others.
Of course, that was just one of the reasons this happened. There were also dangers involved in any negotiation. And in this case, generally, the side of the pirates and bandits was the weakest.