IIRC, Kirk was considered rather bookish and he lacked a sense of humor. In addition, B&B wanted to show Archer as Kirk's boyhood. With these things in mind, I can imaging Cadet Kirk in an academy tactics class in which the professor brings up a battle that the NX-01 fought. When another cadet questions Archer's decisions, Kirk jumps to the captain's defense rather fervently and a bit overzealously, and he begins spouting accounts, facts, and figures. He doesn't stop until finally the professor shuts him up, commenting on the completeness of his answer. Other cadets roll their eyes or comment on what a nerd he is (or what ever the term for nerd is in that era). One classmate, a Vulcan/Human hybrid quietly observes, perhaps seeing that Kirk is like himself, an outcast. After class, Spock comments to Kirk that he was in fact right about Archer, and Kirk thanks him but eyes him cautiously. Later that day, Kirk sees some of the larger and crueler cadets picking on Spock who appears unphased. Kirk jumps in and the fight is on. Kirk knocks out several of them with roundhouse punches, karate chops, and drop kicks while Spock handles the rest quite effortlessly with the Vulcan nerve pinch. Of course, in the scuffle Kirk's shirt gets ripped right across the chest. Kirk, out of breath, makes a quick joke about how Spock isn't even winded. Spock raises his eyebrow in mock contempt, and the two walk away together and their road to friendship has begun.
