Rain brings up the notion that the entire island may be a controlled environment. Basically, it's acting according to a script. This may be why DHARMA chose it. If Locke is able to tap into this script, he knows what's up. Juliet, on the other hand, has been around long enough to see the patterns. Cheating so to speak.
If the environment is controlled, who or what controls it?
Smokey was an abberation in this little game.
The entire island became an intelligence and internalized the psychological studies undertaken by DHARMA.