Thanks for your input!

I have contacted her breeder and she swears that none of her rats bite, nor is maternal aggression carried in her lines.... She thinks it is because the mother "doesn't trust" me because I didn't handle them all the time after I got them. The other rats I got from her are friendly (with the same amount of handling) so this could just be a random nervous / aggressive animal from an otherwise ok line. The mother was bred to my friendliest male, so I was hoping that his personality would show in the offspring.

I think I am going to cull the mother when the pups are weaned but hold back a couple pups from the litter (based solely on temperament not looks) and see how things go with them. If they show any aggression, I will cull them at that point. If the breeder is correct, and I handle these pups as much as possible (putting the mom in another container while doing so) then maybe they will come out ok. I may rethink this after my other female delivers... I'm just hesitant to nix the whole litter because rats are hard to come by here.

Thanks again for your input!