Louis DIDN’T turn into an easily annoyed prick. He had a VERY high tolerance in my opinion. He was nervous about the drop off, he had Ordell on his back, he had to worry about the ATF agent, he had to worry about getting their on time, he had to worry about getting Melanie there, THEN he had to worry about another whole shitload of things getting in and out of the mall WITH Melanie being a bitch to him the entire time. Now, given, Ordell would have popped the bitch in the mouth and shut her up LONG before Louis even began to really crack, but you have to understand the type of person this guy was.
De Niro was playing a Travis Bickle type character in this movie. Someone that takes a lot, but instead of retaliating, bottles up his rage and explodes after a point. Melanie kept riding him and riding him and riding him until he was pushed WELL past ANYONE’S threshold, so he acted in the only way he knew how. He shot the fucking bitch.
