Who is Robin, Opal, and Eddie Pommeroy from Stern Men and what is their importance?

The youngest of the seven sons of Ira and Rhonda Pommeroy, Robin is the closest in age to protagonist Ruth Thomas and is her most regular playmate in childhood. Their daily game is gathering rocks to which Ruth pretends to give birth, in imitation of the Pommeroy parents. They capture all of their expressions and gestures. Robin is a fat little boy and an easy target for strong Ruth when they fight. He cannot pronounce his R's and his father's imitation of this impediment spreads among his fellow lobstermen. Still fat and dopey at 17, Robin marries a pretty, hefty teenager, Opal, from Rockland and they and their enormous baby Eddie move in with Rhonda. Overcoming his speech impediment, Robin becomes a motor-mouth, annoying Stan Thomas on whose boat he serves as sternmen. Robin also regularly drops equipment overboard by accident, but he works so cheaply - since no one else wants him - that Stan tolerates him.