|Kawah Ijen Volcano Photo Credit: http://www.oliviergrunewald.com|
The winter of 1946 held the Donner Party hostage until they'd resorted to cannibalism. Why? 'Cause...terrain+weather=Nature.
Quin Shi Huang's tomb (the one with the famous Chinese statue army) is considered too deadly to fully excavate. Why? All the traps--those planned by Emperor, those created by Nature over centuries, and those that are a mingling of the two.
The Siberian sinkholes, erm, craters that suddenly appeared? The extremely flammable methane from those holes? Why? Nature.
And if Magic is your thing--be it Magical Realism or full on High Mage Elementals--well, the environment is everything: setting, character, quest, conflict, and goal. Think of the classic Connecticut Yankee using foreknowledge of the eclipse to "prove" his magic or James's Seven Forges (beyond the Blasted Lands, there's the whole silver hand thing). Me? I'm working on a fantasy reason for the molten blue lava to appear as a character (in the real-world, the sulfuric gasses cause the blue glow).
One of the many beauties of building up the setting until it too is a character is that it can take an indomitable protagonist down a whole lot of pegs. It can also boost an unlikely weakling into the ranks of hero. It can make a heist far more deadly than a shoot-out, or a sea-voyage riskier than a race through the Dolomites.
And if your cast of fleshy characters is constantly in tune with Nature--viewing her as a threat or as an ally--then their relationship with and to the environment will automatically make Nature into a character. It pays to be mindful of that relationship.
So, that's a long way of saying, Nature is always a character in the story. The question is whether she's a main character or a supporting cast-member.