Afraid I can't help you right now with "N'Kara", as that looks like it'll probably take a bit of research. If Daividh hadn't managed to find this for you the first time you posted about it, then I suspect this is a pretty tough one. :)
"Rayne" is easier, and is possibly derived from:
1. RAYNER - "Transferred use of the surname derived from a Norman personal name. This is of Old French origin ("Rainer"), from a Germanic (Frankish) personal name derived from "ragin" ("advice", "decision") and "heri", "hari" ("army"). (*A Concise Dictionary of First Names* by Patrick Hanks and Flavia Hodges)
2. RAYNA or RAYNE - a Yiddish form of "Catherine", meaning "pure, clean".
3. RAIN, RAINE, RAYNE - literally "rain", popular as a New Age nature name.