2. Gainful Employment
In some versions of the DC Universe backstory, after realising through crisis just how much of an absolute badass the Batman actually is, the fledgling Justice League are quick to offer him a position at the main table. While Batman is much to cool for the often diabetes inducing camaraderie that invariably goes along with the Justice League, he does recognise the inherent value of an entire team of super powered beings being directed toward the goal of fighting crime. To that end, he signs on. But only part-time. And what better way to introduce the Justice League as allies than to have them essentially grovelling to Batman in the hopes that hell join them? Rocksteady would be able to establish the collective power of the League while simultaneously cementing the singular authority of their Dark Knight.