Q: Can a setting, location, or place actually be "a character," as people often say about Gotham City or Bioshock's Rapture, and if so, what exactly does that mean? -- @Jon_Ore
A: Technically, no. No matter how well-developed or intriguing a setting is, no matter how many good stories have been set there or how characters and creators have talked about it, it's still just that: A setting. The action and development, even if they're a reaction to the setting or have effects on the setting, are all things that happen to characters. The setting just provides the backdrop.
Practically, though, they can be close enough that for all intents and purposes, they might as well be characters, with everything that comes with it.