To some people, rats are possessions, like a toy. YOU want the toy, and they don't want to give it up...because its MINE.
They won't ever take care of the rats but they also won't let you have it.
I took in a tiny old sick lady once, and the sister had to "steal" her from her own sister. The good sister offered to take the rat to the vet and pay for the treatment but the parents said No, and the sister said "MY rat, you cannot have it or touch it or go near it" and continued to ignore, neglect and not feed or clean her.
Think of a scenario with small children. A ball is sitting near a child. He is ignoring it and playing with something else. Another child wanders over and starts to play with the ball making it "wanted", and the first child marches over, grabs it and says Mine, and sits there with it preventing the 2nd child from having it. Once the 2nd child has wandered away, the ball is put down and ignored again.
Good luck little boy, lets hope she gets so bored with you, that she says "take it, I don't want it anymore" and then you swoop in with NO words, and grab him and make him safe.