Cobb drives the stagecoach transporting Rebecca to Riverboro at the story's start. Meeting her during the journey, he is immediately charmed by her lively personality and imaginative nature, forging a quick bond. This initial encounter establishes him as an early, sympathetic figure within her new community.

After Rebecca struggles to adjust to her strict aunt Miranda's household, Cobb provides significant emotional support. Following a harsh confrontation where Miranda insults Rebecca's deceased father, Rebecca flees to Cobb's house seeking refuge and begs him to take her back to her mother. Cobb consoles her but refuses her request to return home. Instead, he offers reassurance and presents a metaphor comparing her development to a house built "brick by brick," emphasizing her gradual growth and adaptation to life in Maine. This conversation helps bolster Rebecca's resolve to persevere.

Cobb's presence and actions extend beyond direct friendship. Sheltering Rebecca during her crisis and delivering his pivotal speech contribute indirectly to a crucial shift in Miranda Sawyer's attitude. Miranda's discovery of Rebecca's absence, combined with Cobb's implied influence through his support, prompts her initial realization about the impact of her harsh treatment.