Im confused in Stephanie Meyer's book The Host?

The first chapters are confusing, but the book gets much, much better as it goes along. The aliens call themselves "souls" and in their natural form are 3" long silver bodies shaped like ribbons with hundreds of hairlike limbs called "attachments" which they stretch out to attach themselves to the brain and nerve centers of the host they occupy. The story begins with a "soul" called Wanderer being inserted into the body of Melanie, a human. The doctor who inserts her is named Fords Deep Waters (the aliens have long names referring to their lives on past planets). We share Wanderer's memories of past planets, like the See-Weeds, just to show how different they were from earth. Wanderer is trying to get rid of Mel's consciousness and voice inside her head, because she shouldn't have stayed in her body. Wanderer is reporting back the the "Seeker"--a type of detective whose job is to find and capture fugitive humans. Mel yearns to find her lost love and her little brother who are still human, and keeps throwing memories of them at Wanderer to make her understand the importance of finding them and protecting them from being captured. Wanderer is overwhelmed by the human emotions of Mel's memories, and the conversations with Mel in her head are starting to change her.