First Contact: ‘The Host’ Season 4 Episode 23

Doctor Crusher has a boyfriend, Odan, a Trill ambassador who is negotiating between the peoples of two moons, so generic that no one even bothered naming them properly. When going to the planet hosting the talks, he refuses the transporter, instead preferring the shuttle. However, it’s attacked upon leaving the Enterprise leaving him fatally injured. On his deathbed he reveals he is merely a host body and that the Trill are a joined species and his symbiont is the real Odan who must be saved. With the Trill days away, Riker offers to be the host to try and help save the peace,  leaving Crusher confused that the man she loves is in the body of her friend. Convincing the generic aliens of his identity, peace is negotiated, but Riker’s body rejects the symbiont. A new host arrives just in the nick of time but it’s… a woman. Crusher explains that it is perhaps a human failing that they can’t get used to the person they love changing so much, finally outing herself as a David Tennant era Doctor Who fan.

Listen to the previous episode ‘Half a Life’ here