This happened ten years ago, when I was a teenager, but I can remember it very clearly.
I was walking to meet my friend Peter at his house and for some reason I was feeling a little uneasy (at this age I rarely went out alone, because we used to live in quite a rough part of town). As I got to the halfway point of my journey - my former primary school, I saw Peter waiting for me at the gates up ahead. The gate were at the top of a hill and it was a very bright day with the sun over the hill and Peter was slightly silhouetted, but he is easily recognisable, owing to the fact he was 6'6" even aged 14 and he was wearing a cap I often saw him in! He also seemed to be wearing a white top and black joggers. I broke into a jog when I saw him and as I looked left to cross a small road, I looked up again to see he had disappeared.
I assumed he had run off down the hill as a joke so I called out 'Oi Peter!' then went faster. (I used to be a very fast runner back in the day) Bearing in mind I was only about 30 seconds away from him when he disappeared, I thought it was odd when I got to the gates on top of the hill - he was nowhere to be seen. I carried on running down the path to the end of the road where I had a clear view over some grass to the estate where he lives - if he was up ahead, I would have seen him as the grassy area faced another road, and yet more grass, before you come to his estate so there was nowhere for him to hide or run to.
Confused, I made way to his house, fully prepared to have a go at him when I saw him. He opened the door in a white top, dark joggers and a cap, like the person I'd seen. I asked him why he ran off and he did not know what I was talking about! I believed him and plus, he didn't seem out of breath at all, just relaxed. If he has sprinted that fast, he would have been exhausted.
Who was it? My mum suggested it was a doppelgänger or that he was subconsciously there to protect me as I was anxious when out walking alone.