Easy.
They’re actually aliens form another dimension.
They suffer horrific overpopulation in their home dimension, so they came here instead.
Seeing something so horribly pathetic as humans, they set about conquering us.
After conquering us a couple hundred times, the novelty of it wore off.
So now they pretend to be cute and cuddly while making small attempts on our lives.
Lol! Interesting theory, Darks! Can’t wait for the book to come out! (I want mine autographed, please.) :)