John Holbrook is the son of a tanner who taught himself Latin by candlelight. Unable to afford tuition at college, he has traveled to Wethersfield to study with the Dr. Reverend Bulkeley. He arrives in Wethersfield at the same time as Kit. Just like Kit, he will be on a journey to find out who he is and to become his own person. Since John’s path at times runs parallel to Kit’s, he serves as a sort of mirror protagonist in the novel.
A Puritan, John is a bookish and dignified young man who is often kind, though a bit prudish. Kit, however, notices a change in him once he arrives in Wethersfield:
One week in Wethersfield seemed to have changed the dignified young man she had known on shipboard. Tonight he appeared to be a shadow, hanging on every word from this pompous opinionated man. Even now he dared not assert himself but held the Bible uncertainly in his hands and ask, “What would you have me read, sir?” (6.24)
One week in Connecticut and John has become nothing more than a suck-up. Uncle Matthew drives the point home when he says that John is a “young toady with no mind of his own” (10.28).
Over the course of the novel, John must learn to act and think for himself, especially in the area of love and politics. Is he a Royalist or not? Is he going to passively marry Judith even though it's Mercy he loves?
Our questions are answered when, toward the end of the novel (Chapter 16), he breaks with Dr. Bulkeley by joining the militia as a doctor to fight Indian attacks in Massachusetts. As Mercy points out, he had to “prove something to himself” (16.100). When John returns from the militia, we see that he has indeed become his own man. He marries Mercy, his true love, and returns to study with Bulkeley under the condition that he “will teach me theology and medicine, but I will think as I please” (21.4).