Betty seems like she's looking out for Joseph as soon as he arrives at Mr. Tow-wouse's inn. She tells her mistress that "the man in the bed was a greater man than they took him for," thus ensuring that he gets some extra-special treatment (1.15.1).
Yeah, well, Betty has a special treatment of her own in mind for Joseph. Not only does she nurse him back to health, but she also tries to make a move on him once he's all better. Joseph's not interested, which provokes her into a scary rage: "One moment, she though of stabbing Joseph, the next, of taking him in her arms, and devouring him with kisses, but the latter passion was far more prevalent" (1.18.10). Um, girl, which is it?
Luckily for our boy Joseph, Betty doesn't act on either emotion. Still, she seesaws back and forth enough that we'd warn Joseph to steer clear.