Harpies are both feared and trusted.
They are feared as they are unusually aware of dirty little secrets, crimes committed in other cities and if they have a mind to are able to raise a Kindred to the heights of legend or to destroy their reputation forever.
Harpies are generally from the Toreador clan but some have chosen the Brujah or other clans to hold the station. Harpies communicate with other through various secret channels. As such it is a very bad idea to cross a Harpy for all Domains will hear of it soon after.
Harpies consider themselves to be the "voice of society" and can be quite brutal with their comments. Newcomers to a Domain are advised to ensure the Harpy is aware of their arrival so proper arrangements can be made for safely entering the Domain. Some Harpies charge the arrivals a "boon" or favour for such assistance but not always.
When dealing with Harpies it is best to remember that they are generally extremely skilled in social skills, quite vain and will always make sure they come out ahead in any deal. Treat them with respect, keep your business short, leave them in peace and you may end your visit to an Elysium without too much trouble waiting for you on your return home.