In a medium saucepan, bring water and salt to a boil.
Slowly stir in the grits and reduce heat to low. Cover and simmer for 20–25 minutes, stirring occasionally.
Remove from heat, stir in butter and cheese until melted and smooth. Set aside.
Season shrimp with salt, pepper, and cayenne pepper.
In a large skillet, cook bacon until crispy. Remove and drain on paper towels.
Add shrimp to the skillet and sauté in bacon fat until pink, about 2–3 minutes per side.
Add garlic, lemon juice, parsley, green onions, and cooked bacon. Stir and cook for another minute.
Spoon grits into bowls and top with shrimp mixture. Serve warm.