Who is Elisabeth (Howard) Elliot from Shadow of the Almighty and what is their importance?

One of eight children, twenty-one-year-old Elisabeth meets Jim Elliot as they attend Wheaton College and share many of the same classes. She is a year ahead of him school, but they sometimes talk after classes. After quite some time, Jim asks her on a date. She accepts, but then cancels. Her friends can't believe she's done this and explain to her that she has missed a once-in-a-lifetime opportunity, because Jim Elliot doesn't ask girls out as he considers them to be non-essentials. Something that he can eliminate from his schedule. A couple of months later, her brother Dave invites Jim home for Christmas, and she gets to know him through long talks into the wee hours and watching him interact with her brothers and sisters and helping fix things around the house.