Mr. Frank is the leader in the annex because the hiding place exists above his business. Miep, Mr. Kraler, and others who help those in hiding are Mr. Frank's business associates. He, with their help, put the whole concept of living above the warehouse in the hidden loft together for the benefit of the others. Mr. Frank and friends are the ones who made the plans to move food and supplies into the hiding place months before the families are forced to leave their lives behind. Mr. Frank is also a very calm and respected gentleman who is not easily offended. He is kind and accommodating to the needs of his guests and their helpers. He is smart, organized, and has saved money to help them survive for a very long time. Mr. Van Daan wouldn't be a good leader because he is too selfish and easily provoked to anger. Mr. Dussel comes in a few months later as a guest; therefore, he doesn't have any standing to be the leader anyway. Mr. Frank, then, is the best possible choice and he takes his duty as host to all of his guests very seriously.