Marlow listens to Jim, helps the young guy get job after job, and takes care to see Jim's story through to the end. He's the older, wiser guide to the young, foolish Jim. Sounds like a mentor to Shmoop. But Marlow is much more than your typical guiding hand. He's a a bit of a protagonist, himself, as we learn everything through his perspective. In that sense, he also guides us readers through the story, drawing our attention here and there to the details that count.