Cassius Dao

From Hidden Frontier

Cassius Dao (Hal Alpert) was a joined Trill who served as the Dao symbiont's 17th host body ("The Battle is Joined)".

In its 16th life, Dao fell in love with a woman, a romance that affected its incarnation as Cassius so deeply that it led him to break the Trill taboo against reassociation, which forbids joined Trills from re-establishing intimate relationships with people from its former lives. Dao was expelled from Trill as a result.

Cassius developed a neurological disorder to which only Trills are susceptible. Doctor Henglaar was unable to treat Dao, noting that the symbiont's strength had kept the host alive for as long as it did.

In his desperation, Cassius Dao turned to his former student, Zen, to accept the symbiont. Zen secretly joined with the Dao symbiont, subjecting himself to exile if his secret is ever revealed. Cassius died shortly after the operation.