I have NO idea how amnesia works or the manner in which a person gets his memory back. So if the manner I use sounds incorrect, trust me, it is. I'm flying by the seat of my pants here. I am not sure how Abby got her hippo, but I read a fan fic on another site and I liked their story of how Abby acquired Bert. I liked it so much I am using it here. The story is called "A Gift of a Hippo' at fanfiction.net, written by pygmymuse. Thanks for your unwitting contribution to my story.