My best friend and I (both females) are 9 years apart in age. I met her when she was 16, but I didn’t realize it until the next day when we talked some more, I just assumed she was about my age. I had gone to an outdoor “oldies” concert with some other friends who were my age, and then we all met my best friend and we all clicked, mostly because of what we had in common. I think it’s pretty rare to have as big of an age difference as we do, especially because she was so young when we met. If I met her today (20 years later) and we were 9 years apart, it wouldn’t be weird at all. I think I just got lucky that she was very grounded and mature and looked a little bit older than she was and she spoke like an adult rather than like a teenager. But it was mostly what we had, and still have now, in common that has kept us such good friends. We have a similar background too (with regards to beliefs and upbringing and culture) and I think that helps, but is not absolutely necessary. We are also very respectful to each other. Without that, you really can’t have much of a friendship with anyone. We always laugh because, although we live in different cities, whenever we get together it is likely that we will show up dressed alike and we often discover some “new” interest that we want to share with the other person, but 9 times out of 10, we have both discovered the exact same new interest at the same time. It still amazes me. I often tease her that she is my twin, but without my anxiousness and emotional outbursts.