My older brother and I were really close when we were little. I posted these in a different thread... but it seems appropriate here too:
Then we grew up a bit and grew apart a bit at the same time. He went off to the marines the day I turned 16. He was in it for 6 years and, although we talked, we weren't really that close during those years. Within the past 4-5 years, we have grown pretty close again. Our interests and lives have much more in common than they did during my high school years.
My sister and I are probably the closest. After my brother and I started drifting apart, I began to spend more time with her... even though before, she was our mutual enemy, being the only sister and all.
All 3 of us:
My sister and I probably have more in common (art, music, books, etc.), but all three of us have intertwining stories that make us all close. I wouldn't trade my siblings for anything... and the older I get the more I love the time I am able to see them, which regrettably, isn't nearly enough.