I have a step dad. He's been around since I was 13, and while I still call him Pete, he knows that it means dad. He's one of the most wonderful people in my life. He treats my mom like a goddess, and between my mom's three kids, and his two, we have a big, crazy family, that only gets closer as we all get older. I think of his kids like my own brother and sister, and his family is my family. I used to come home from school every day and sit on his office floor and just talk for an hour. Now we sit around and smoke pipes and drink beer together.
My husband has a step-dad and step-mom of his own, and he is as close to them as he is his biological parents. And since you don't just marry the man, you marry the family, I feel like the luckiest in-law in the world.