My Heart Is A Well

Am I full or am I empty? Come closer and take a look. The deeper you go, the darker it gets I do not know surface for I am intimate with depth You can only know me if I want you to, though I rarely ever do. I am for you or against you depending on how you handle me. One wrong choice and you're done for life. I am desperately wicked and deceitful above all things, who can understand me?