Hello 8 spider,
Perhaps it's no coincidence that the harlot has turned into a Spider Bride after receiving the gift of the Haarlocks ... perhaps they thought it funny to have one of their servants turn into a spider-like creature, given that the spider plays such an important role in their heraldry.
They have more monstrous and sinister servants btw, for example the Gilded Widow and the Widower and the Mirror Daemon. One of the themes outlined in the Legacy books is 'servants fearing their master's return'. It sure gives one pause to think, if the likes of the Widower and the Spider Bride actually FEAR Erasmus Haarlock ....