Complexity and Contradictions in Characters

A writer cannot go wrong with Janet Burroway's book, Writing Fiction, eighth edition.  The following is a bit on characterization and complexity:

Conflict is at the core of character as it is of plot. If plot begins with trouble, then character begins with a person in trouble; and trouble most dramatically occurs because we all have traits, tendencies, and desires that are at war, not simply with the world and other people, but with other traits, tendencies of our own. All of us probably know of a woman of the strong, striding, independent sort, attractive only to men who like a strong and striding woman. And when she falls in love? She becomes a clinging sentimentalist. All of us know a father who is generous, patient, and dependable. And when the children cross the line? He smashes crockery and wields a strap. All of us are gentle, violent; logical, schmaltzy; tough, squeamish; lusty, prudish; sloppy, meticulous; energetic, apathetic; manic, depressive. Perhaps you don't fit that particular list of contradictions, but you are sufficiently in conflict with yourself that as an author you have characters enough in your own psyche to people the work of a lifetime if you will identify, heighten and dramatize these conflicts within character, which Aristotle called "consistent inconsistencies."

                                                                     pp. 131, 132.

I am in the throes of writing a novel with a central character, an ex-Marine, who is a pushover for babies. Yet as a kid he slapped a baby who wouldn't stop crying.  He hates his sister for his dependency on her as he slogs his way into alcoholism.  Yet it is she who he turns to for help along the way.  We'll see what his feelings are in sobriety.