Who is Webster Pommeroy from Stern Men and what is their importance?

The oldest and smartest of the seven sons of Ira and Rhonda Pommeroy, Webster is mentally destroyed at age 14 by the sight of his drowned father's body on the dock of Fort Miles. He stops growing and speaking. He cannot read a book. He is the childhood playmate of protagonist Ruth Thomas, who remains a loyal life-long friend. The only child old enough to work, Webster cannot become a sternman because of acute seasickness. He wants to be a farmer and keeps a few chickens.