What happens when you can totally be yourself around someone? The perks, the struggles, the flaws, the imperfections. You can laugh, share jokes, tell secrets? Another extension of you that you can rely on, to help you when you fall, to be there when you need, and to help you succeed. They look into your eyes, and simply say "I got yo' 6 Babe!"
What happens? .....you fall in love!