I was about 8 years old at the time, and loved to watch those scary paranormal shows.
My family and I had just moved to another city, to this small but cozy apartment. The layout was roughly as follows: immediately after stepping inside, to the left was the dining table, the living room was further ahead and to the right was the kitchen; these were not separate rooms. There was a hallway to the end, which led to the rest of the rooms - three bedrooms and a small service closet.
My brother must have been about 1 and half years old. It was late afternoon, dark, and the poor thing had thrown up in the kitchen. The entire living room and kitchen smelled like puke, so I retreated to my bedroom, which was the first door in the hallway. My bed was next to the wall, facing the door. I decided to lay down, watching the door. A few minutes went by, and I was thinking about just staying there for the night when something crossed the doorway.
It was a small silhouette, shadowy, at the time I thought it was a little girl but I'm not sure anymore. Short hair, about my height at the time. She/He - It seemed to be grabbing the door and swooping in, then disappearing into thin air.
I stood up and checked the hallway, but there was no one there, as expected. I asked my parents, but they were in the kitchen with my brother the whole time. I don't have any other siblings.
I let it go after a while, but apparently it didn't let go of me.
Fast forward a few weeks, maybe. I'm at school, standing on the counter, copying some notes.
Suddenly I feel someone behind me. Out of the corner of my eye, I see that she is a girl, short-haired and about my height. She breathes out, and I could feel the loose hair from my ponytail get blown into my face.
I turn around. No one there, or nearby. No one saw anything either.
I never put much thought into it. Until a few years ago.
I was telling my experience to a few of my parents' friends, since we were all talking about that. My mother's face drops, and she starts telling the story of how my brother spoke to a boy in his room, whose voice would quiet when she walked in. He doesn't remember the boy or anything for that matter.
One thing that caught my attention, however, was that my mother told me that my brother told her that the boy swooped in from the door, like the one I saw. She still notes how his expression when he demonstrated her was enough to give her chills.