A minor character for the star trek crew I posted a few weeks ago. I think having a Cardassian on board might be interesting. He's a member of a once-powerful group, now serving under and among people who are unlike him, and might be uncomfortable with his own Cardassian identity, having come of age during the occupation of Bajor.

You could also do some things with gender roles here, since on Cardassia it's more often women who pursue the sciences and men who command starships, and he's in the opposite situation here.