Many have speculated on whether or not the ending is real or Travis Bickle’s fantasy. Scorcese himself has come down on the side of reality and I tend to agree with him. If it’s reality, then that throws an ironic twist on what ought to be a real downer of an ending. It may not be entirely logical when you think about it, but the other possibility doesn’t really fly either. The letter from Isis’ parents contains details that you wouldn’t expect from Bickle’s sort of delusional fantasy. I also doubt that his fantasy would involve him going back to driving a cab. In his mind, he’s a hero so I’d expect his delusions would be somehow more, well, heroic.