So I am originally from England, born and raised up until about 4 years ago now. Now living in the beautiful country of Canada. Just kidding it is beautiful but it's not home, you know?
Anyways I'll jump right in. I've been in my current house for about a year now. It was good for a couple months and then I would say after about 6 months weird occurrences happened.
I would say it first started off with me noticing weird pictures (drawings) coming through the paint on my wall which weren't noticeable until we moved in. The drawings included two nude people having sex quite like the image or drawing in the movie "The Orphan" where she drew or painted her adoptive parents in a sexual act. Anyways I found that slightly odd and then I started noticing sentences and I would try to make them out. Some said stuff about death and others just nonsense. Apparently the boy previous to me was a troubled teen, very rude and just a problem child.
So I'll fast forward, weird occurrences became after a couple months nothing before we got our dog Winston, a border terrier who seemed to bark at random things and growl at the stairs as if someone was walking up them when nobody would be home. He was scared of a specific corner that he doesn't dare to go in.
One night I was doing my makeup, I was going to a house party. I was stood in the bathroom with the door open which is next to my parents' bedroom door which was closed. Out of nowhere I hear a rumbling and three loud fast hard footsteps towards the door as hard and loud as you can imagine, sprinting towards the door. I screamed of course, as did my mother.
It was so realistic we believed it to be a intruder so we grabbed weapons and barged the door open to find nobody there. We saged the house and stayed elsewhere that night. That was just one terrifying event in this house.
It's possible someone drew some pictures on the wall which was later painted over. As Rook says, it's possible to see images under paint, depending on how many coats were painted over, the colours and pigment used in the underneath image. Given the right light, angle, it's possible you're actually seeing a physical image, not a paranormally (is that even a word?) conjured one. (Hope that made sense!)
With that said, I have to say 'hmmmm', as I feel it's likely the two are connected. Horrible scary footsteps and nudey rudey images. But this would depend on why the images were seen by you, who was behind these images. If some teenage boy did draw things like that on a wall...umm. Maybe it was a one time thing, getting back at his parents, or a girlfriend, during an isolated one off event spurred by a bad temper. Or, and this is the worse case, someone was pretty freaking disturbed and very creepy.
Just a question about the image. What style is the image? I mean does it look armature, as in messy, scribbled, like someone didn't really care what they were doing? Or was the image more in line with an artistic style, abstract, intentionally simple or detailed, old fashioned or modern, like someone cared about the image they were drawing/painting?
Some people paint pictures on the walls of their home as part of the decor. Some people are into erotic art, so it may be an innocent image left by someone who lived there. If this is the case it's most likely unrelated to those horrible footsteps.
(I haven't seen The Orphan, actually I think I have but it was a Swedish film (I think) maybe you're referring to a remake I'm not aware of, not sure.)
These footsteps are awful. I'm glad your Mum heard them too, it helps when things happen to you together rather than alone! Well I think everyone here will agree they were very obviously designed to scare you and get your attention.
Please take a look at a cleansing/shielding method, Rook has one on his profile. You don't have to put up with creeps who get off on scaring people.
Take care.