Destiny Adrift. Interstellar Fleet, #4

One fleet Three ships Many destinies An unidentified alien entity has free run of the starship, Bres, but that's the least of Waylis's worries. She left behind her family, her friends, and her entire species on her home planet, the first world to be visited by the Interstellar Fleet. Her decision has grown to be the greatest regret of her life. As a shapeshifter and a relic of humanity's evolutionary past, among the humans she's a freak, and they take every opportunity to remind her. To the ship's scientists, she's little better than a lab rat.
They want her help to stop the uninvited visitor from taking over the Bres. But as it stands, she has more in common with the alien than the crew. Destiny Adrift is book four in the enthralling space mythic adventure, Interstellar Fleet.