I am looking for a book/series written in the 1980's about twin boys. One is stolen at birth by evil monster demons and is raised by them to be evil. I believe I remember that the land in this book is divided by a line where one side is always night and is where all the evil lives. I think these twins had magic and are the children of the king. Can anyone help me? I can't remember the author or the title. I never got read the next book in the series and would love to find it again.
Could it be The Lost Prince by Paul Edwin Zimmer?
Were it not for the awesome power of the Hasturs, the creatures contained by the dark border would overrun mankind. As humans reeled from the constant onslaught only to rebound, the darkness searched for another path to victory. It stole a princeling and raised him in Shadow, teaching him how to command the living and the dead, how to usurp his brother's throne through magic, and how to turn humans against themselves. And then it sent him home...
80s Fantasy novel evil twin and swordplay was on the suggested questions on the sidebar. The querent (who self-answered), had an additional detail that "A particular detail that sticks with me is that they fed him the breast of his nursemaid and the milk in it got him to like the taste of blood/raw human flesh".
There being a side that's light and a side that's dark matches up with the Dark Border entry in Zimmer's Wikipedia article:
In a conflict that was long and hard-fought, that saw great losses suffered by the Hasturs and their allies. The sons and grandsons of Hastur, with the aid of the great Elf Host of Mananan and Nuadan, succeeded in driving the Dark Lords from the world and once again raised the weakened barriers.
But they were not entirely successful in ridding the world of evil, many of the lesser creatures of the dark; demons, vampires and goblins the least powerful of the evil servants of the Dark Lords - lingered and forged a realm on the slopes of the mountain chain that ran almost the entire length of the main continent. Using dark magic, they caused a shadow to perpetually cloak their realm making it safe from the sun, which was an anathema to them, and from the powers of the Hasturs.
Could it be the War of Light and Shadows by Janny Wurts?
Born on a splinter world, Lysaer and Arithon are half-brothers raised apart in enmity. Cast through a Worldsend Gate, they arrive in Athera, the ancient world of their ancestors cloaked in the fog of the malicious Mistwraith.
Only the combined powers of two half-brothers can challenge the Mistwraith’s stranglehold: Arithon, Master of Shadow and Lysaer, Lord of Light.