Ch 1: Visible Child
The problem with having a child who could be seen by mortals was that they were always trying to save the boy. Granted, not all mortals could see him; but it seemed that some of the more magically-inclined ones, who liked to call themselves witches and wizards, were fully capable of seeing the young spirit.
Pitch used to take the child with him to work at night, leaving him at a set location, like a park, while the older man would gift the mortal children with nightmares. Once in a while, the Nightmare King would return to find a human attempting to rescue the boy. Apparently, bare feet and frosted clothing meant "homeless" to mortals.
Needless to say, this eventually led to Severus being left in the lair while his father swept the world at night. The night-mares (no pun intended) tolerated the young immortal, making the nights a little less lonely. The books, "borrowed" from libraries around the world, were his only other source of comfort.
But soon... very soon, Pitch would return from a long nights' work to spend some time with the gift that Jack Frost had unknowingly left him after their last battle.
...tbc...
Note: This story is less a full-story, and more a set of misc. ficlets (short and long) revolving around the idea of Severus Snape as Severus BlackFrost (son of Jack Frost and Pitch). Surprisingly enough, mpreg is not going to be included in this story.