The greatest aspect of any Star Trek series is the characters. Star Trek features a wide variety of characters that serve to enrich the universe the writers create. Deep Space Nine had some of the most compelling characters from a Star Trek project since the original series. The Trill, for example, provide a great deal of range with their characterization. They're a humanoid species who bond with a worm-like alien known as a symbiont. The Trill implant the symbiont within a host, of which only a select few receive the honor of becoming, and they receive all the memories from the symbiont's previous hosts. The most popular Trill in Star Trek is Jadzia from Deep Space Nine, who hosted the Dax symbiont.