User blog comment:EmpyreanSmoke/Supernatural Q&A/@comment-96.91.247.202-20150930180453/@comment-24834479-20150930234216

Some suggested they are a form of Tulpa, some think they are an attribute manifested, and some think they were born from darkness.

Not that I know of.

Some probably do, but in general they don't.

They don't leave humanity alone, but they don't necessarily eat people.

There are most likely monsters that don't disturb humanity.