Just relax. It's much more formality than anything else. Partners don't use to eat new analysts during the breakfast. They prefer managers and consultants!
Serious now. You don't have to make anything different during these or any other interviews or meetings with Accenture people. If they feel you are though enough, its fine, if not, you will not make it up. About your passion, just an advise. Write down your personal objectives before starting with the firm and check them against your life-style with some frequency. It will help to avoid a lot of pain.