Who is The Thief from Anecdotes of Destiny ; and, Ehrengard and what is their importance?

The Thief appears in the story, The Ring. He is described as a silent and potentially deadly man, who Lise meets when she goes to a covert in the trees near the path back to her house. He allows Lise to leave, but he rejects the ring she offers him. He does, however, accept her handkerchief.