In a medium saucepan, bring 4 cups of water to a boil. Add the grits, 2/4 teaspoon salt and 1/4 teaspoon pepper. Whisk well to avoid clumping. Reduce the heat to low and cook until the water is absorbed, 10-12 minutes. Remove from heat and stir in the butter, cheese, and 2-3 dashes of cayenne pepper. Cover until ready to serve.
In a large skillet, fry the bacon over medium-high heat. When crisp, remove the bacon with a slotted spoon and place on a paper towel to drain.
Add the shrimp and another dash of cayenne pepper to the bacon grease and sauté until pink, about 3 minutes. Immediately add the onions, garlic, parsley and lemon juice. Toss and remove from the heat. No need to salt the shrimp, since it's going into bacon grease.
Divide the grits onto plates and top with the shrimp mixture and bacon pieces.