I thought that Harry's behavior was natural for someone who has always had to depend upon himself alone and who can never expect an outsider to *finally* help him to escape from the Dursleys' treatment, given that so many people have failed him. I personally didn't see him as playing the martyr but as continuing to endure what he has been forced to endure throughout his life, and trying to not unnecessarily add that load to Snape and Draco's shoulders as well, given that he has no hope of the situation improving, anyway. ... I guess I sympathize the most with Harry as well ;-) Snape is just soooooo prejudiced and ignorant despite being so clever in other ways....