User blog comment:EmpyreanSmoke/Supernatural Q&A/@comment-27006668-20151026141204/@comment-24834479-20151026235322

1. All of the monster souls and Leviathan inside him twisted his view of things.

2. It was him, but he was being twisted by the leviathan

3. He was able to use the millions of souls to hold them back

4. Even with the souls he couldn't completely overpower them, so they eventually dug their way up.

5. Just the two.