Honestly, galactic dragons often feel like a shortcut, a way to skip the heavy lifting of constructing a believable interstellar society. When an author drops in a cosmic-scale leviathan that can swallow stars, they're immediately handing themselves a ready-made source of conflict, awe, and power. The world-building tends to orbit around the dragon, literally and figuratively. Its biology dictates the laws of physics; its sleep cycles might define an empire's calendar; its territorial disputes become the backdrop for entire wars.
The real trick is whether the dragon feels integrated or just glued on. In the worst cases, it's a spectacle that overshadows everything else, making the rest of the setting feel flimsy. In the best, like maybe in some of Alastair Reynolds's stuff or Ann Leckie's universe if she ever went there, the dragon's existence forces fascinating societal adaptations. Do civilizations worship it, mine the asteroids caught in its wake, or build their entire philosophy around avoiding its attention? That's where the interesting questions start, moving past the cool factor to ask how a culture would actually live with a god-like creature as a neighbor. I've bounced off a few books where the dragon was just too overpowering, leaving no room for the human-scale stories I crave.