Leonard Bast is the one person who literally changes things for everyone, including himself. He is poor, suspicious of everyone, and desperately wants to gain status through reading about finer things in life. His friendship with Margaret and Helen begins very slowly. He suspects them of every imaginable ill, thinking they are using him to learn secrets about his business. He is always concerned with self-improvement, and constantly nagged with financial worries. He is married, but is married to a former prostitute, Jacky. She represents the worst of the worst -- somewhat "trailer trash" if you will. Leonard begins to develop some redeeming qualities when he forms a tentative friendship with Helen, which turns sexual when they are both at terribly vulnerable times in their lives. Immediately, and for the rest of the novel, Leonard is filled with remorse. He is in turmoil, which actually helps him forget his money woes for a while. Despite the continuous troubles that came his way, they were "overshadowed by Remorse" and was unable to see "beyond his own sin." (Forster, 835) In spite of his marriage to this garish woman who used to sell herself to men, he still feels guilty about his sex with Helen. He never once considers that she is to blame, when he earlier had thought she was conniving in everything she did. When Leonard goes to tell Margaret, whom he has learned to respect, about his sin, he is beaten severely by Charles (Henry's son) and is killed by the heart attack that ensues. His thoughts before, during and after this attack are what shows his change -- perhaps the most notable in the novel. He feels a "conviction of innate goodness" and it is described not as his death itself that saves him, but "the idea of death saves him." (Forster, 841) One of his last thoughts is that he was "ashamed, but had done no sin." (Forster, 841) Leonard no longer cares so much about appearances as he does about doing the right thing, which is a totally foreign concept to him.
Overall, E.M. Forster certainly succeeds in painting accurate, though somewhat exaggerated portraits of the idealism, and materialism that can coexist and compete within the upper classes in England, along with the debilitating effect that poverty can have on a life. His characters, Margaret, Henry and Leonard all three represent good, evil and poor respectively, and all three achieve marked growth in the novel. Margaret and Henry both achieve this growth partly due to Leonard, who achieves the most notable growth shortly before his untimely death in "Howard's End."
Forster, E.M. "Howard's End," Great Novels of E.M. Forster: Where Angels Fear to Tread, The Longest Journey, A Room with a View, Howard's End. New York: Caroll & Graff Publishers, Inc. 1992