First of all, Grete would probably have the role of Manolin. At first, she would take care of Gregor like Manolin takes care of Santiago because Gregor is to her what Santiago is for Manolin, which means he wants to teach her something. She too would liberate herself from her parents as Manolin does. Finally, she would also take charge of someone’s life but not Santiago’s: her family’s.
Secondly, Gregor’s parents would in every way be like Manolin’s parents. To them, money would come before anything else and they too would push their son to go fish to bring back money. They would not take much care of their son and would desert him, letting him get out in the middle of the night if he so wishes, as long as he brings back fish to the house. Furthermore, they wouldn’t care if he’s happy or not on his fishing boat.
Thirdly, Gregor would be at the same time Manolin and Santiago. Gregor would be obligated to fish on a boat that brings back a lot of fish and he would be forced to it by his parents, like Manolin. Yet, in the end, he wouldn’t dare to oppose his parents and would still go on the boat. In spite of that, he would be meticulous and would control everything, especially his lines which would be very straight. His work would be all that he could think about, except for Manolin Grete, to whom he wants to teach something. He also would not have a woman in his life and would stay locked in his house, isolated from the outside world. His only dream would be of finding himself alone in a fishing boat with Manolin.
Furthermore, the villagers would probably laugh at him, forcing him to isolate himself even more than he already is.
Finally, the three roomers would be tourists or old men. After Santiago’s miraculous catch, they would go see the skeleton and would mock Santiago and probably want to expulse him from his home. They would possess more money than Santiago and so would be, from that point of view, Americans who move to Cuba to dominate the Cubans. But, like the old men, they would stay grouped together during their attacks against Santiago, like cowards.