My sister and I are 18 months apart and we fought all the time mostly verbal, but sometimes physical. She is the oldest, but I have always been taller and meaner than her. I was a fighter when I was growing up. I remember the last physical fight we got in, I beat the fire out of her. She left and went to some friends and said she wasn't coming back til I was gone. When my mom and dad came home they were furious! When my dad saw her, he told me I better never touch her again and if I did whatever I did to her he would do to me, i.e. if I blacked her eye, he would black mine. Funny thing is, even though I could stand to be near her for more than 5 minutes and used to fight with her everyday, I would kick anyone's a$$ that even looked at her wrong!
We are so much closer now and even though she still annoys me sometimes after being around her 24 hrs, I love her to death and I know I can always turned to her and vice versa. We are just very different individuals that have come to appreciate that about each other.