I lived a good portion of my teenage years in a house in California with my dad and two younger brothers. The mood in the house was often negative. Most of it started when my dad invited one of his girlfriends to live with us. She was very nice to me and would tell me stories about her experiences with ghosts and things.
It began with small black "blobs" kind of scooting around the house. We'd mostly see them out of the corner of our eye. They'd either scoot along the floor, or be in the kitchen doorway and then "hop" off to the side. Sometimes they'd be on the walls, kind of gliding down from the ceiling. When they were on the walls they always appeared to have wings. Just two triangular wings coming out from the side of this blob of shadow/distortion that they seemed to be made up of.
The only time I saw one straight on I was up late watching infomercials and doing homework. One of the blobs flew right across the top of the screen, kind of slowly. It appeared in the middle and flew off to the left. I tried switching channels thinking it was the TV show, but it didn't go. It flew to the left edge of the TV and disappeared. They never interacted; they just kind of went about their business. I think my cat often saw them and chased them when we couldn't see them.
The next thing to start was the footsteps in the hallway. The footsteps were loud and angry and would start at the front door and end in the corner where my dad's room and the bathroom were. It would usually only happen if only one person was awake or home at a time. It almost never happened when I had my friend over and we slept in the living room.
Eventually the footsteps escalated to hearing the front door open and close or slam, hearing the cupboards in the kitchen slammed, and even hearing dishes broken. I would get up to check the door and it would always be closed and locked and nobody ever found any broken dishes.
Then we started hearing footsteps on the roof. Anyone who heard it always heard it in their bedroom, or wherever we were sleeping. Sometimes people heard it at the same time but it would be going from the middle of the house towards the outside. So a different direction for everyone. My dad would usually hear the footsteps followed by a thud on the deck outside his room but nobody was ever there. It would usually happen around 1am to 2am and didn't matter who was awake...
At first we thought it was my ex stalking me. Because we found footprints in the grass, a muddy one the wall of the house outside my bedroom window, and another muddy one on the roof. The shoe size was the same as mine, which was true for my ex, who was also very heavy and would explain how loud the footsteps were.
The thing was the footsteps were not just loud but you could hear the ceiling kind of crackling under the weight of the "person" and we had an attic. The only entrance to it was in my dad's bedroom closet. My brothers went on the roof to investigate, the older of the two was tall and weighed over 200 lbs, and even jumping up and down their footsteps were very quiet, I'm assuming because sound diffused through the attic.
My cat seemed quite disturbed by the footsteps and would look up at the ceiling with his ears back even before you heard the footsteps and then follow the sound of them across the ceiling. I always knew when they were about to start because my cat would stop playing and start staring at the ceiling.