User blog comment:ImperiexSeed/Are fairies really capable of snekaing into Lucifer's Cage? If so, how?!/@comment-1509826-20120103193956/@comment-3481504-20120103200216

Actually, angels can (and have) appeared in their true form on Earth, but generally don't.. Examples are, Castiel, Lucifer and Michael. Anyways, name one thing that Doc survived that a demon couldn't. I'd bet that if a demon and Doc were on Earth and a nuclear bomb went, the demon, even thought it's host would die, would survive, whereas Doc wouldn't have any remains to re-assimilate.