Who is Hadley Slegg from Songs of the Humpback Whale and what is their importance?

Hadley Slegg is twenty-five-years old. After Hadley's father dies, his mother sells their farm and moves to Carroll, New Hampshire. He has a younger brother named Cal. Hadley then goes to work at Sam's orchard. He has a relationship with a fifteen-year-old girl but Hadley dies tragically when he falls off a cliff.