The Fallen Hero in Gothic Literature
We know the seemingly pitch-perfect Mr. Darcy is all the rage, but even he has a little bit of a brooding side—and you can definitely thank Gothic novels and their descendants for the bad-boy-as-good-guy hero. Lord Byron, a soldier and Romantic author, pushed the bounds of the antihero and allowed for the creation of such prickly yet irresistible characters as Charlotte Brontë's Mr. Rochester and Emily Brontë's Heathcliff.
In keeping with most of the Gothic aesthetic, the appeal of the fallen hero was that he played by his own rules—a rebel-with-his-own-cause. It's not just that he's unpredictable; it's that his decisions have an internal logic dependent on the character's own moral code. Pretty hot stuff to throw in the face of Enlightenment thinkers who were all about laws that would hold true in all cases, at all times.
Chew on This
Robert Luis Stevenson's The Strange Case of Dr. Jekyll and Mr. Hyde offers you a protagonist-antagonist two-for-one special. Check out what it's like to be your own worst enemy.
By the time Oscar Wilde was writing, Gothicism was undergoing a transformation. As a standalone genre, it was seen as old hat; but as a warehouse of super-cool literary elements, it was a writer's playground. In The Picture of Dorian Gray, Wilde appropriates the movement's traditions and turn towards the macabre in the creation of his decidedly not-nice-guy protagonist.