Nuclear regions of galaxies apparently play a disproportionately large role in regulating their formation and evolution. How this regulation works, however, remains very uncertain. Here we review a few recent X-ray studies of our Galactic center and the inner bulge region of our major neighboring galaxy, M31, and focusing on addressing such questions as: Why are the majority of supermassive black holes (e.g., Sgr A*) so faint? What regulates the Galactic nuclear environment? Furthermore, what impact does a recent active galactic nucleus have on the ionization state of surrounding gas? These studies have provided new insight into how various relevant high-energy phenomena and processes interplay with extreme galactic nuclear environments and affect global galactic ecosystems.