Nelo Angelo
Dark Knight
I have been looking and searching after enjoying lots of DMC4 gameage, I went looking for answers to Nero's existence and I found this:
Nero Theory
In the top right hand corner of this article it gives use a theory of Nero and how there are a few pieces of evidence which are quite compelling.
It basically says in a nut shell that when Vergil became a "full" demon is humanity was given up and thrown away which gave birth to Nero. Then when Dante defeats Nelo Angelo, it trys to fuse with its former self but only manages to equip itself to his arm (Probably after all the fighting Nelo had done had made him extremely weak and was unable to reclaim the reincarnation of his former host).
Nero Theory
In the top right hand corner of this article it gives use a theory of Nero and how there are a few pieces of evidence which are quite compelling.
It basically says in a nut shell that when Vergil became a "full" demon is humanity was given up and thrown away which gave birth to Nero. Then when Dante defeats Nelo Angelo, it trys to fuse with its former self but only manages to equip itself to his arm (Probably after all the fighting Nelo had done had made him extremely weak and was unable to reclaim the reincarnation of his former host).