I was around 12 years old, when I got the big bedroom for myself. Me and my brother are only 1 1/2 years apart, and for some reason we used to sleep in the same bedroom. So, when I finally got it for myself, I was very happy. Keep in mind, that we have always slept in this room, and for years it felt normal. Nothing creepy happened.
But already on the first night, of me sleeping alone, something weird happened.
The layout on the first floor, was as follows: from the kitchen on the ground floor, the staircase went up to the first floor, where as soon as you landed on the top step, my bedroom door was on your right site. Then the next door was my moms room, then a turn to the left, where my brothers new room was and at the end was the door to the bathroom.
Everyone was asleep, when I heard it. Someone was walking up the stairs. But I knew that everyone was asleep. My bedroom door was open, I would have noticed if anyone were walking downstairs.
I lay still as a corpse. And it just continued. I knew sound of my stairs and how many times a step would sound for a person to land on the first floor. But right at the end, it stopped.
My heart was pounding like I was being chased and my mind raced. But I convinced myself that it must have been my imagination.
The next night the same thing happened. Just like the night before, everyone was asleep and suddenly it sounded like someone was coming up the stairs...
I thought to myself, that I wouldn't be afraid. I've had seen a lot of things already at that age, and I knew how to make it go away... But just as last night, whatever was walking upstairs, stopped at the last step.

The third night I convinced my friend to stay over. I hadn't said anything to her. But it was a way for me, to get to sleep in the living room instead of my bedroom, since we had a pullout sofa down there.
From the living room, we could see through the kitchen directly to the staircase. But we have slept in the living room before and nothing ever happened.
But then, my friend woke me up in the middle of the night. She was afraid, because she felt like someone was watching from the staircase. I looked and couldn't see anyone - it could have been my brother who wanted to come down to get something to drink or mess with us. But no. There was no one. Nothing but this eerie feeling of someone watching.
We went back to sleep but my friend wanted to go home as soon as we woke up.

I then asked my brother if he had ever witnessed something like that. And he said no. That it must be my imagination. Even trying to make fun of me, saying that he could sleep in my room that night, if I was still afraid of sleeping alone.
But I didn't want him to. I was not afraid! I at least tried to tell myself that...

Then that night, the steps didn't stop as they did before. My bedroom door was almost closed this time. But it suddenly started to open. And on the doorframe closest to the stairs, two hands was wrapped around, like something was trying to poke its head around, pooling itself up from the staircase. I began crying, screaming for my mom, but she didn't hear me. And that made me even more afraid, since her bedroom door was beside mine, only a wall, as thin as paper, between us.
I sat up, looked directly at the thing in my doorway, who was now becoming even more visible.
Its fingers longer than a persons. Darker than the night, and something looking like eyes peering inside my room. But the thing was, it wasn't looking at me. It was looking down. At the foot of my bed. Like it was afraid of something in the room, afraid of going inside. And then it disappeared.

For days I was shaken up. I didn't tell my mom about it, because my child brain felt like she had betrayed me for not hearing me, when I yelled for her to come safe me.
But then a family member came to our house. She has, like me, always been seeing stuff that others couldn't and hearing things, sensing a lot of crazy stuff - a whole story for another time.
She told my mom, that we should look at the little crawlspace/attic between the two floors. That it was important. But she didn't say why.
My mom then found the key - mind you, we have never used this space, since it was too small to use for storage or anything like that, and the key almost didn't even open the old trapdoor, because it was so old and hadn't been used since we moved in.

To our surprise, an old painting of a little girl lay in there. We didn't know her or where this painting came from. But she felt so familiar...
My family member then said something that still to this day sends chills down my spine... (and remember I didn't tell anyone about the last encounter, and hadn't talked to this family member for a while, before she came to visit and told us to look in the attic).
"So this is how she looks... The girl that protects you from the dark." She said it, with a smile on her face, like she was happy to finally see an old friend. "She told me, that you and your friend was afraid of her. But you shouldn't be. Your brother has accepted her long ago..." I almost dropped my jaw at that.
"She lived and died here many years ago. Before you or even the last owners lived here. And she told me, that she didn't like the last owners. Didn't like your father either... She lives under the staircase, so that she hears who moves up and down and can spring into action when needed." she smiled at my mom when she said the part about my father, and I remembered how many times that he stumbled up or down the stairs, like someone had pulled a rug from under him. He even yelled at me one time, because he thought that I was the one who did something, to make him fall...
"She protected you from the dark not long ago - though not the living dark this time... And she says that she will always be watching over you when you are vulnerable or have forgotten to raise your mental walls."

After that, I must admit that I was still a little afraid when I heard footsteps on the staircase. But I reminded myself, that at least the girl under the staircase had my back, if anything dark, living or not, came for me... And I always remember to keep my guard up, both physically and mentally... Always checking, if people stumble when they are around me, for no reason, like its an indication of their intentions.