Maybe Katsuro? It looks fitting for him. It's a Japanese name that means "strong".

Art is by me, sorry the pic is so tiny. xP
I need a feminine but threatening name, since... y'know... she's a dragon. She's ill-tempered, emotionless and aggressive, and isn't very fond of having to be around people or other dragons. She lives in the mountains on a tundra, and is rather small for even an eastern dragon, only 6 feet tall.