There are pros and cons to going into business via a third party; Severus hates not taking credit for his work, and hates not being recognized where he should be, but it's much safer and more effective, like this. At least two Death Eaters are in this city, one of which (by the pain in his arm) sounds very powerful and very angry, and he's fairly certain he knows who it is. Having no desire to mingle with his peers, Severus is, for now, remaining a silent partner in someone else's enterprise.

Beyond his pride, however, there are other annoyances. Case in point, no one taking him seriously when he's trying to sort out supplies. This is the third merchant trying to rip him off, and the black-haired man is already seething silently, staring into a tray of poorly filtered onyx powder, listening not to the people around him but his own internal mantra against murder.