Hmm. We're taking 6 'cuz he was about to be sacrificed by Lust. AS far as I know we are mercs hired by 'the professor' to sabotage the plans of at least one of the seven rulers of the city.
As for injecting you into the story, I could simply turn around and ask to an indescript patch of shadow :"Mistress, Is this the one we are looking for?" And you can step out of the shadows from where you observed all that has passed and answer "No, kill him" or "yes, he's the perfect sacrifice, bring out the sharp knives and the rubber boots", or even "Yes, let's get him to our safehouse and set up a meeting with our professor"