Who is The Boys (Tom, David, Andrew) from Islands in the Stream and what is their importance?

Tom is the oldest boy and probably the favorite. He fondly remembers Paris with Ginny and Thomas, much to Andrew's vexation. Andrew would rather do something or hear stories about doing something. While David struggles with his swordfish, Tom looks on and worries about his safety. Andrew tries to help in any way he can. David loses the fish at the last moment but learns to be a man, which in Hemingway's estimation involves endurance and strength.