Essentially every frontier Fort and Indian Agency had a Sutler. The Sutler was a Government licensed private merchant who sold commercial goods (tobacco, coffee, blankets, tools, etc.) at the Fort and/or Agency for a profit. The Sutler could sell his merchandise to anyone;
soldiers, Indians, and civilians. However, he could not 'legally' sell alcohol on the Reservation.
Under the British system in North America, the Sutler ('Factor' in their terminology) was a Government paid employee like the Indian Agent himself. He wasn't allowed to make a profit. In fact, he was required to sell his merchandise to the Indians at 68% of costs. He was reimbursed the difference by the British Government. The British idea was to buy the Indian's friendship with 'good deeds and good deals'.
The 'British Factor System' was adopted by the U.S. Congress after the Revolutionary War but abandoned in 1822 under pressure from the States to 'privatize' the practice.
Bargain prices now were replaced with exorbitant prices. Low interest credit was replaced with usury.
Erastus Rogers, the Sutler for the Seminole Agency began moving his merchandise inside Fort King on Christmas Day, 1835. He was worried that the Seminoles might take revenge on him for the high prices and interest payments he was charging them and destroy his materials, ruining his profit for the year.
He was just being a good business man. He had costs to cover and the high risks involved in getting his merchandise through the forest to his store justified his high prices and high interest charges to the Seminoles. He didn't realize how high the risk was. He may have been a good businessman, but he was about to be a dead one.