We find the story of the rich young ruler in all three synoptics, but the gospel of Mark has some unique details (Mark 10:17). In Matthew and Luke, he just shows up somehow, and asks his question (Matt. 19:16; Luke 18:18). But in Mark, he runs up and he kneels. In all three, when Jesus gives His answer, the young man is sorrowful and goes away. But in Mark alone, we are told that in giving the answer, Jesus looked at him and loved him. My supposition, which connects to some other odd statements in the New Testament, is that that this young man was John Mark himself, and this is why we have the additional details. If so, the story has a good ending.