They say that even though humans were his favorites, humanity isn't the only race that God created.
Although there are some that reside on earth, there are other worlds that they live on. Although the angels of heaven and the demons of hell are aware of all of them, there is one race that have become the subject of campfire tales (or at least as close as you can get with Angels and Demons).
They say that they were god's first attempt at creating humanity, and that in many ways, they were far more successful. They were stronger, lasted longer, and even more efficient, But while they had many of the same emotions as humans, as well as they're will power and stubbornness, they still had the distance of angels.
All of them, that is, except for one.
Although he goes by many names, the angels call him "The Man with Many Souls". The reason behind this is because his race had souls so powerful, that even the weakest soul among them was more powerful than all the souls on earth, as well as in heaven and hell put together.
His soul is sought after by demons and angels alike, but none have been able to claim it, as not only does he evade them, but he has also never died, he only changes.
Even though any angel or demon you ask will tell you that The Man is just a legend, many will still flock like vultures to him if the ever manage to get a whiff of him.
They say that when the man finally breathes his last, it means that the earth is doomed.
But everyone knows it's just a fairytale