Humans are irrational creatures. Vulcans are only supposed to do what makes sense, so Spock often behaves in sharp contrast to the other characters on board the ship. This can be seen most readily in "Strange New Worlds," when other characters may be feeling the magnitude of a situation, but Spock confronts it with the utmost sincerity.
Actor Ethan Peck spoke about this dichotomy in an interview with TrekMovie.com. The outlet brings up how the original Spock actor, Leonard Nimoy, struggled with finding the balance in the character. This could be seen in an interview Nimoy did with BBC and later republished by The Washington Post, where he stated, "I think it's a matter of interpretation. There are those who would say he has no emotion. I think the opposite is true. He's a very feeling, sensitive person who does have emotions, but he also has emotional control."
To TrekMovie.com, Peck responded, "Being Spock is quite a pressurized experience and a delicate endeavor because he is in control of so much of his emotions. It's quite challenging, at least for me as an actor. What's too much emotion? What's too little? What's too Vulcan? What's too Human? So I'm constantly wrestling with those things." It's clearly a natural reaction to playing Spock, but judging from his performance on "Strange New Worlds" so far, he's nailing it.
