That's clearly a dog. Most bears don't have elongated tails, and they generally have a different build. I don't even think that suspiciously ursine paw is even attached to that dog.
Pointless nitpicking aside, this feels a little lacking, although I do like it. The writing is good, and you're going in a good direction with the whole "invasivion" aspect, as well the bizarreness of random emotion bears, but it needs a little work (at least, in my opinion) to get across to the viewer. Sorry that I can't really provide anything more constructive than that. Perhaps you could do something in regards to why it only manifests in monochrome images.
And if I may enquire into that Addendum: how are these images asscosiated with the bear if the bear doesn't manifest in them? What exactly sets the occurences in colour photography apart from another, unrelated phenomenon?