In The Witch of Blackbird Pond by Elizabeth George Speare, how has John Holbrook changed since coming to Wethersfield?

When John Holbrook first came to Wethersfield, he was hesitant to contradict Reverend Bulkeley.  Reverend Bulkeley was his teacher and mentor.  John Holbrook had moved to Wethersfield to study under him.  While both men had differing opinions, John Holbrook kept his ideas to himself.  Kit observed how John Holbrook acted around the Reverend Bulkeley:

With a flash of pleasure, she saw John Holbrook approaching, but her impulsive greeting froze as she saw that Reverend Bulkeley...

When John Holbrook first came to Wethersfield, he was hesitant to contradict Reverend Bulkeley.  Reverend Bulkeley was his teacher and mentor.  John Holbrook had moved to Wethersfield to study under him.  While both men had differing opinions, John Holbrook kept his ideas to himself.  Kit observed how John Holbrook acted around the Reverend Bulkeley:

With a flash of pleasure, she saw John Holbrook approaching, but her impulsive greeting froze as she saw that Reverend Bulkeley had the young man firmly by the elbow. In the shadow of his teacher, an extra staidness had fallen over the young divinity student, and his smile was lukewarm with dignity (The Witch of Blackbird Pond, Chapter 5).

John Holbrook was more serious around his mentor.  He appeared to have adopted many of the opinions of Dr. Bulkeley.  He admired Dr. Bulkeley and his vast knowledge.  John tried to align his beliefs with Dr. Bulkeley.  Finally, he could not do this any longer and he joined the militia as a "way of breaking with Dr. Bulkeley" (Chapter 16).  He was also timid around Matthew Wood.  When it was wrongly assumed that John wanted to marry Judith instead of Mercy, he was too fearful to speak up.  He chose to remain silent rather than speak to Matthew or tell the truth to Judith.

After John Holbrook returned from the militia, he changed in many ways.  He openly confessed his love and affection for Mercy.  He also became more outspoken about his views and opinions:

"Dr. Bulkeley is everything I ever thought him to be, a great scholar and a great gentleman," he explained. "In politics he is obeying his own conscience, but I think he is mistaken. We have come to an understanding. He will teach me theology and medicine, but I will think as I please" (Chapter 21).