(Author’s note: it is eleven at night and I hadn’t even been planning on writing this but oh well here ya go)
Generally, when people found out that they were in a relationship, people directed their questions at Spock. ‘How do you put up with him?’ they would ask, and Spock would sass his way through an answer, because he was Spock, and that’s what he did.
They never really asked Jim how he put up with Spock, which was a pity, really, because his answer would be brilliant (no point being modest; he knew he was right). But, he had come to terms with the fact that people would always assume he was the tricky one in their relationship.
Spock, for all he claimed to be a calm, logical, in-control Vulcan, was…well, was not that. He pretended to be, of course. He kept his expression perfectly schooled at all times, never let the mask slip for even a second, because he was a Vulcan, and Vulcans Do Not Have Emotions.
For Captain Kirk, this wasn’t a problem. Spock’s perfect calm had helped the ship and its crew out of many a tricky situation, and he was grateful for that. For Jim, however, it drove him absolutely mad. Because when he said that Spock never let his mask slip, he really meant never. Not even when they were together, alone, in the privacy of their own quarters.
This is what made Spock the difficult one out of the two of them, because even though Jim was pretty good at reading his expressions, and even though he could usually get at least a vague glimpse of what he was thinking through the bond, there were still walls up that not even he could break through. It drove Jim mad, not being able to just know, but he was working on dealing with it.
He reckoned that Spock was trying to deal with it too, in his own way. Jim was gradually sensing more and more through the bond, and Spock was trying to be more open, if the quick contact between their fingers whenever they passed one another was anything to go by.