Who is Eddy Marshall from To Have and Have Not and what is their importance?

Eddy Marshall is described as a tall, hollow-cheeked, sloppy "rummy" with joints slung wrong. Marshall gets Morgan the charter with Johnson and is hired to travel with them. When Morgan prepares to smuggle a dozen illegal Chinese immigrants into Haiti, however, he refuses to take Marshall along. Marshall then gets an official to add his name to the crew list and stows away. When Morgan find him, he is unhappy about his presence, but later gets him to cover the Chinese and lock them belong decks, and then gun the engines as he murders his erstwhile partner, Mr. Sing. Marshall's having gotten his name on the list makes it safer to keep him alive, and Morgan knows that no one will listen to his drunken ravings.