in this au, dream (and by extension nightmare) can feed off of both positivity and negativity.
however because of key differences in their biology, it is-was usually only a last resort and extremely painful because they were not built to house it. the reason dream eats it, is because he believes that once negative emotion is completely eliminated from someone, the automatic response is to generate positive energy. Also, he considers it rude to eat from the people he helps unless offered, so he makes due with torturing himself to stay fed.
















