Astraeus (The Oceanstone Initiative, #1)

When Dr. Sakota Thorell signed onto the mission to scout out a new, habitable planet, she knew discovering extraterrestrial life was always a possibility. But she never expected to find an alien adrift in space, nor for that alien to be so intriguing. Sakota feels an instant and undeniable attraction to Astraeus, but he represents a million possibilities, and just as many threats.

There are others hunting Astraeus, and his rescue may cost Earth its last hope.