This sounds a lot to me like what I have come to understand to be "4th dimensional" beings. There are some similarities here with : "shadow people", Jin, and there may be some elements of "black goo" involved. Visits in the middle of the night (the closer to around 2 am the more convincing) suggest the time of the late night when the border between 3rd and 4th dimension is finest, and this is when a lot of 4th dimensional "encounters" tend to occur. Cats are also claimed to be able to see into the 4th dimension, which would explain the story of the cat hiding under the table and staring at the kids. I believe this concept of "black-eyed kids". It makes sense in the larger scheme of things...