My mother will only let me get one rat!!!?

Ok, I have done some research about rats and they need to be accompanied by another rat! My mom with only allow one, I would probably get comment's saying to not get a rat at all or to somehow convince her to let me have another rat. But I really want a rat and went as far as cleaning the whole house for a month though I'm only up to day ten. Once I reach 31 days I will only get one rat, and believe me there is no convincing her to get another rat. I keep on fearing that the rat will have health issues or maybe agressive. I need help or advice on what to do!!!