This is quite an interesting phenomenon, very frightening, like shadow people.
it is my belief that these black eyed kids are intent on taking the life force out of a person. Like the shadow people do, energy being a food source to them. I do agree they need permission, which is also part of the alien abduction scenarios. This goes into the beyond life area with the alien abductions,where the abductee agrees to experience the " abduction" and what ever else that entails. However I don't know if that is the case with the black eyed children.
To me they seem inter dimensional, but there is some other connection here, it could be alien or it could be low vibrational demonic beings using a human disguise. The whole thing is very creepy and we are still learning about the phenomenon so like they say there is not much to go on yet. I don't think it is an entirely modern issue, there have been cases of strange beings through out history.
One other thing to ponder is many metaphysical researchers discuss is dimensions /time lines merging. That is quite plausible when people are experiencing all sorts of bizarre things such as the feeling of time standing still. Seeing into the future in sudden day dream like moment.