It's someone that was sent to the lost camp after Ethan and Goodwin failed too. I think he was sent after the hunting party scene. They found out that Jack, Sawyer and Kate can be useful. Since Sawyer was seen to be angry. They knew that Jack and Sawyer have some romantic intentions toward her. All about the love. Thanks to Jacob who reported back, and quite possibly sent to the lost camp to scout out more possible suspects. So Ben sent himself to find Jacob, but decided to play with Locke's mind because he is a man of faith, thinking he was after him. Ben failed to find Jacob and ran off thanks to Micheal.