Become Mine And Mine Alone

(REWRITE OF THIS BOOK IS UP! It is called "Obsessive Love".)
(I do not own the cover, Undertale nor any of the characters besides my OC's, they belong to their respectful owner. For some reason, I just see Error in the front instead of passive Nightmare.)
Error, Forced God of Destruction and Destroyer of Universes was largely unknown unlike Ink, the Creator and God of Creation. Their fights were unseen by the AU's, none of the Monsters knowing about the Destroyer as Ink doesn't want them scared and Error gave no shits if anyone knew him or not.
But Error's job is a complicated one, one that he is forced into, and he has to get involved to destroy the worlds. He doesn't touch the Original AU's, but the copies that Ink makes have to go. It was only a matter of time before something happened.
Ink, in a middle of one of their fights, blinded Error, hurting him much more badly then ever before. In panic, Error ported into one of the Original AU's. Ink, fearing what Error would do, tells Dream about the Destroyer. Now the hunt is on for the broken, blinded skeleton.
Meanwhile a blinded Error has been taken under the wing of another powerful Monster who has fallen for the broken Destroyer at first sight.
But sweet love is truly beyond him. It is a obsessive love, a unhealthy love unlike any other.
Nightmare would do anything for Error, and would do anything to keep him by his side as he goes about taking over all the AU's. Now to convince Error that he should be his and his alone.