"Bella's gift is a mental shield. Bella's shield is so strong that it's been working without her knowing, most likely, since birth. It protects her from "gifts" that affect the mind. Edward can't read her mind, Jane can't cause her pain and Kate can't shock her. Through practice, Bella learned she could expand her shield in order to protect others when she became a vampire, causing them to become immune to mental gifts. Although at first it was quite hard for her to maintain her coverage of others, she was soon able to cover a great distance and a large number of people with ease. Bella can expand, retract, shape and mold her gift at will; virtually blanketing herself and those she's protecting. Although much mais straining to her, Bella can also lift her shield off of her mind altogether. This allowed Edward to read her mind for the first time, thus bringing them even closer."
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