Heheh. Nice looking girls. One might even say... Larger than life!
Both of our girls used to nibble gently on our fingers... like scraping their teeth on us, rather than biting. That was only for the first couple of weeks. Now, though... the second you put your hand near either one of them, they just lick, lick, lick, lick, lick.
My rats love to nibble on me a lot, sometimes nibbling a bit hard, I see it as trying to groom me for they love going under my nails. If they ever bite down a little too hard where it hurts just 'EEP' in a high pitched tone and they most likely will stop. The first time time my boy Shin accidently bit my toe the momma's 'eep' scared him to the point to where he cuddled in my hair, licking my ear for about two hours.