"Nighteyes" is essentially a condensation/combination/variation of various nicknames I've had over my life, because I really do -- er, did -- have exceptional night vision.
"Daniel" comes from a character description I once developed. "Daniel" sort of took control, so to speak (fiction writers know exactly what I mean), and the character description became the first chapter of a novel that I have yet to finish. Like the Daniel in my novel, Daniel Nighteyes was raised by his maternal grandparents. His grandmother, a devout Christian, named him after her favorite Bible story, Daniel and the Lion's Den.
What is rather interesting, though, is that "Nighteyes" turns out to be DANIEL'S alias as well!