Final answer:
Frederick Douglass was most surprised by the stark contrast between his expectations and the reality of life in the north. He had believed that the non-slaveholding population in the north would be poor and uncultivated, but instead, he found a thriving community of colored people living in comfortable homes and displaying a spirit of determination and protection.
Step-by-step explanation:
The most surprising aspect of life in the north for Frederick Douglass was the stark contrast between his expectations and the reality he experienced. As a former slave, Douglass had believed that the non-slaveholding population in the north would be poor, uncultivated, and devoid of wealth and refinement. However, upon arrival in the north, Douglass found the people living in clean, new, and beautiful houses, enjoying the comforts of life and displaying a spirit of determination and protection for one another. His mistaken beliefs about the north and the thriving condition of the colored people he encountered there were surprising revelations for Douglass.