My opinion on Jack

I'm really beginning to dislike Jack (Sal). He is incredibly immature and irresponsible and runs away from his problems rather than stay and find a way to solve them. He always expects more for him doing nothing and thinks that the world will fall into place by him just sitting their. During his time spent with Henri, Jack doesn't do much to help their situation except for being an extra burden and on top of that, he is "in love" with Diane, Henri's significant other. So pretty much, Jack takes Henri's kindness for granted and in return acts as an adulterer. "I walked by a jewelry store and had the sudden impulse to shoot up the window, take out the finest rings and bracelets and run to give them to Diane. Then we could flee to Nevada together. These were mad dreams." Jack doesn't even think about working for the Jewels! He doesn't even fantasize about earning them so he could give them to Diane, he just wants to steal them so as to exert as little effort as possible. 

Then there is the scene with Henri taking his father out to dinner and Temko acting completely rude during the gathering. Rather than Jack trying to tell Temko to calm down, "I gave up, I got drunk." When situations are too hard to handle for him, he shrinks to an immature child and cowers away from the problem.