I had a best friend. He was almost exactly the same as me, except he was... different. He followed me around almost everywhere I went. I only ever saw him during the day, and when it was cloudy, he almost never showed up. He never spoke a word, he kept quiet. I sometimes wondered what was going on in that wide head of his. He is the only person that understands me, that's why I called him my best friend.
It only took me 6 years to realise, he was my shadow.