Generate a Villain Backstory From a Single Contradiction

A villain built from a checklist of traits reads like a checklist. This starts from a single contradiction, works out the formative event behind each half of it, how the villain currently papers over the tension, and one small habit that gives the game away to an observant reader.

Generate a backstory for a villain built from a single contradiction: {CONTRADICTION}. Explain the formative event that created each half of the contradiction, how the villain currently resolves the tension between the two, denial, compartmentalising, believing both at once, and one specific habit or tic that reveals the contradiction to an observant reader without the villain realising it. Keep the whole backstory to one page.