Elwin Ransom, the main protagonist in C. S. Lewis's Space Trilogy, serves as a sort of stand-in for Lewis himself. A relatively ordinary man, Ransom is a linguistics professor who uses his teachings to understand the world around him. He is a sort of middleman between the two different planets (his own and Malacandra). Because of this, Ransom is frequently diplomatic. At one point, Ransom observes,
At last it dawned upon him that it was not they, but his own species, that were the puzzle. That the hrossa should have such instincts was mildly surprising.
Ransom's willingness to understand the alien creatures while questioning his own species makes him a man of great empathy. While Weston and Devine may hold more shockingly cruel opinions on the alien creatures, Ransom cares about them as fellow sentient beings.
The second important characteristic of Ransom is his bravery. While initially fearful of the new planet, he quickly overcomes his fear with courage and adventurism. Also, being motivated by a strong sense of morality, Ransom is able to face terrifying situations with bravery and confidence.
Lastly, Ransom is a trusting man. This can be seen perhaps most clearly in the opening of the novel in which Ransom meets Weston and Devine. When the two offer him a drink, he begins to feel suspicious and notices some sinister characteristics of the pair. Nonetheless, being a friendly and trusting man, he accepts the drink and is ultimately drugged and taken to another planet.
With physical characteristics that suspiciously match Lewis's own, it becomes clear that Ransom is not only a stand-in for Lewis's own beliefs, but a figure of who Lewis would have liked to be—a moral, brave, and generally loving man.