The interplay between Kirk and Spock in “The Devil in the Dark” is fascinating.
Kirk: I want this creature killed on sight. I will lose no more men. Spock: It’s such a pity to see such a unique creature perish. Perhaps we could try to capture it? Kirk when he actually encounters the creature: Maybe we can talk it. Spock upon seeing Kirk with the creature: Kill it Jim! Kill it now!
Funny how Spock lets the logical veil slip when he thinks Kirk might be in danger.