Its her 6th birthday next month and she wants a rat. From what I understand if she has one, she'll actually have to have 2 as they're happier in pairs.
My main concern is do they smell?
Closely followed by how tame, friendly are they likely to be? I remember having gerbils and hamsters as a child and been too scared to pick them up as they used to nip, or jump out your hands and disapear for days.
Also - is the novelty of having a rat likely to wear off for a 6yo quite soon? I know that I will have to be responsible for supervising feeding and cleaning out. But I also don't want to be the only person who ever gives them any attention.