[Jacob:] It was really too bad he couldn't hear Bella's thoughts. Then he'd annoy the crap out of her, too, and she'd get tired of him. (13.83)
Jacob believes that a large part of Bella's attraction to Edward lies in the fact that he can't read her thoughts. Does he have a point, and how might their relationship change if he could?
[Edward to Jacob:] "I'm hearing you more clearly – it's a matter of familiarity and concentration… [Jacob:] It bugged me a little, but for no good reason, so I shrugged it off. (14.18)
Now that Jacob has clearly taken sides with the Cullens in heart and in mind, Edward can hear his thoughts more clearly. The intimate mental connection with Edward makes Jacob uncomfortable, but "for no good reason." What might be a good reason, then?
[Carlisle to Jacob:] "If you were in our shoes, how would you proceed?" (14.153)
By asking Jacob for his opinion on hunting, Carlisle shows his respect for Jacob, and also intends to make him feel like part of the family.
[Jacob:] "Occasionally, the mind-reading thing saved time. For example, maybe I wouldn't have to make a big production out of the accusation about what was going on with Charlie. Edward would hear exactly how furious –." (15.164)
Jacob is glad that he can communicate his emotions to Edward instead of having to express himself out loud and discuss the matter in front of Bella.
[Edward to Jacob:] "Go, Jacob. Get away from here." (16.258)
After Edward reads Renesmee's thoughts to confirm that she's not monster, he also realizes the pain this revelation causes Jacob, and that being with the happy family might just break him. So he tells Jacob to leave.
[Jacob:] I let the practical instincts take over, letting her feel that too. She hesitated for a second, but then, tentatively, she seemed to reach out with her mind and try to see it my way. (16.75)
Jacob is able to communicate his natural killing instincts as a werewolf to Leah. Why might mind reading be a more effective tool in this instance than verbal explanations would be?
[Edward to Jacob:] "He has one of the purest, sincerest, kindest, minds I've ever heard." (17.150)
Edward can see that Seth is a person with no second agenda. He follows his heart and acts selflessly toward others.
[Edward to Bella:] "The f–" He swallowed. "It… the baby likes the sound of your voice… He's happy." (16.216)
Edward discovers that he can hear the baby's thoughts and that the baby is doing fine. How might a mother's experience of pregnancy change if she could read her baby's thoughts?
[Bella:] I felt irritated again, like Jacob was stealing my lines – and delivering them all wrong. (23.87)
Bella has trouble accepting that Jacob loves Renesmee as much as she does and that he's in tune with her concerns about Renesmee.
[Bella:] …I realized that most of the werewolves were unprotected. I was about to reach out to them when I realized that… if the Alpha was under my shield, the rest of their minds were every bit as protected as his. (37.15-16)
Bella learns that, thanks to their mental connection, protecting their leader will protect the others from Jane's powers. Great. On the flipside, it's safe to assume that if Jane got to Sam, she would hurt the others as well.