Odan is a Trill, a joined species where a humanoid host body houses a parasitic worm-like creature that is the true intelligence. The symbiote moves from host to host, but the Odan identity remains the same.
Odan met and fell in love with Dr. Beverly Crusher of the starship Enterprise during a peace mission. The two of them became lovers. During the mission, Odan’s male host body died and Odan temporarily took over the body of Will Riker, until a replacement host could arrive. The new host was a female, and although Odan still wanted to pursue a relationship with Dr.Crusher, Beverly was unable to cope with the constant changes that Odan goes through. The two parted as friends.
They met again a few years later during a mission to transport a dangerous Trill criminal. Odan attempted again to renew their romance, but Beverly was very uncomfortable around her. Despite her discomfort, it was obvious that Beverly still cared deeply about Odan, and that concern came to the surface after the criminal, Dalor, escaped and took Odan hostage. Beverly was able to rescue Odan, but the two women ended up trapped on the starship with him and his mercenary crew, while Crusher’s Enterprise crew mates attempted to recapture Dalor. The two women fought side-by-side, and were able to hold off Dalor’s men until the Enterprise was able to rescue them.
This experience helped the two of them to bond again, and although Beverly was still not ready for a relationship with Odan, she admitted that it may be possible someday.
Odan first appeared in the TNG episode “The Host”,episode #97 and in comics in Star Trek The Next Generation Annual #4.