Bajoran vedek who warned Sisko that an ancient prophecy foretold disaster for the wormhole when Cardassian scientists arrived.
Yarka is a Bajoran vedek in Destiny who had recently lost his rank after protesting the Vedek Assembly's support for a peace treaty with Cardassia. When Cardassian scientists arrive to help build a communications relay through the wormhole, he tells Sisko that an ancient prophecy predicts that three vipers will cause the temple gates to burn.
He presses Kira on her faith and her duty to the Emissary. Events follow the prophecy, though not in the way Yarka feared: a comet broken into three fragments passes through the wormhole and makes the relay possible.