Hmm.. Sounds like a very interesting series! Well, I actually had the name from Greek mythology. She's one of the primordial forces, born from Chaos. If you're interested; here's a link to the Wikipedia article.
Nyx Wiki
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Improbe Amor, quid non mortalia pectora cogis!
Ire iterum in lacrimas, iterum temptare precando
cogitur et supplex animos summittere Amori,
ne quid inexpertum frustra moritura relinquat..
Callous Love, to what do you not compel the mortal heart!
She was again obliged to tears, to again pray and beg
and humbly bend her spirit for Love,
to let nothing remain untested and not die pointlessly..