When I was fifteen, I had gotten into a fight with my mother's boyfriend and I holed myself up in my room to surf the web on my laptop while I was laying in bed.
I heard footsteps come down the hall and figured my mother came to talk to me, but I didn't feel like talking so I shut my laptop and pretended I was sleeping. I wasn't facing the door.
I felt the door open, and I realized it wasn't my mother, it was her boyfriend. He's a really big guy, my mom is a tiny mousy thing.
He didn't say anything, which I thought was really weird. He's a loud guy, he doesn't appreciate silence and he's not the dramatic type.
He walked over to me and stood next to my bed for a few seconds. My eyes are wide open and I can see the shadow cast over me by the light of the hallway behind him. At this point I had no idea what I should do, I had been pretending to sleep and I didn't want to stop but I was also extremely uncomfortable. I was getting ready to say something like, "Uh, hey, weirdo! Get out of my room!" when suddenly he reached down and grabbed my lower back, digging his nails in. Immediately I tried to scream for my mother in response but I couldn't move anything and for a few seconds I stayed like that in full panic mode, heart pounding, adrenaline pumping. Seconds later I could move again, I flipped over to make him stop and found no one there.
I immediately starting crying in some weird mixture of relief/disappointment and horror. Then I composed myself and went downstairs to hug my mother. I didn't explain what had happened because I was still really weirded out.
I want to dismiss it as sleep paralysis but I wasn't asleep. I was wide awake the entire time. My back was sore for the rest of the night.