From SuspireWiki

Earl is the Title of Tribute bestowed upon a vampire who conquers a domain, adding it to the territories of the Invictus and earning the right to rule it (as determined by the Inner Circle). The vampire so titled appends the name of her domain to the title (for example, The Earl of Montmartre). As with a Viscount, an Earl who loses control of her domain must remove it from her title. The Honorable precedes the Earl’s name in introductions. No more than one vampire may hold this title for a domain at a time. Only Final Death or a declaration of the Inner Circle can free the title to be conferred upon another.