When I was 17 years old I babysat a lot. I can vividly remember this one babysitting experience. This sounds extremely cliché but it was on a dark and stormy night.
I was watching this little girl named *Siobhan. She was a sweet little girl and her parents were supposed to be back well after midnight. So Siobhan and I sat and watched TV, played games, typical activities for when you're babysitting.
One of Siobhan's friends came over to play and since it was raining outside and it was really cold and was also dark we wound up playing hide-and-seek. Since I was the oldest it was my duty to seek them first. So I counted to 20 while they went to hide. Keep in mind these were two little girls who couldn't keep from laughing so they gave away their hiding position pretty quickly. After I was done counting I saw the door at the end of the hall moving like there was someone behind it. I automatically assumed that that was where the two girls were hiding. So I walked down the hall and I made a show of saying "gee, I wonder where they are?!" I figured I had wasted enough time pretending to look for them when I already knew where they were, behind that door that kept moving. So I walked quietly to the door and I stepped into the room and I looked behind it and I said "gotcha". I was completely taken aback when I saw there was no one there. And the laughter I had been hearing wasn't coming from the two girls because the two little girls decided to hide on the opposite side of the house.
I quickly found the two girls and I told them that playtime is over and that we were just going to sit and watch TV. Siobhan's friend had to go home a half hour later so after her friend left it was just Siobhan and I in the house alone. I decided it was time for Siobhan to go to bed because it was already way past her bedtime so I put her into her bed and I went into the living room to study for a test. I kept hearing what sounded like a door open, and I thought Siobhan was trying to come out to get a glass of water or to say she couldn't sleep, I was waiting for the typical excuse from a kid. But every time I checked on Siobhan she was sound asleep. So anything I was hearing wasn't coming from her, she wasn't the cause.
Her parents finally got home a little after midnight, and when Siobhan's Dad was driving me home I told him what had been happening and what I had experienced and he said that he had experienced the same thing and he had purposely not told me anything to see if my experience would be the same as his. I can honestly say that that was the creepiest and most scared I had ever been.
* Name Change
On the other hand...
I am also curious if you babysat for the family again and if you had further experiences.