by Joe Haldeman (Published by Analog and Ace)
Winner, Best Novel in 2005
Two aliens have wandered Earth for centuries. The Changeling has survived by adapting the forms of many different organisms. The Chameleon destroys anything or anyone that threatens it.
Now, a sunken relic that holds the key to their origins calls to them to take them home—but the Chameleon has decided there’s only room for one.