In the year 2135, Ych'a was a member of a team of V'Shar agents led by Denak to the planet Trilan, to pursue a race of mutated Vulcans called Fri'slen plaguing the outpost there. Ych'a was one of three mission survivors, along with Denak and T'Pol. (ENT novel: Kobayashi Maru)
Ych'a later married Denak. In 2155, Denak was only able to tell that Ych'a was still alive because of the telepathic bond they had and he hadn't had any communication with her. The lack of communication was due to her working with Trip Tucker on a clandestine mission for the V'Shar in Romulan space. Denak asked for help from T'Pol, his old friend and co-worker, in tracking Ych'a down and bringing her home.
Ych'a used a mind-altering mind meld on her clandestine mission to make Centurion Terix of Romulus believe himself to be the V'Shar agent Tevik. This belief made Terix an asset on the mission and allowed Ych'a to bring Terix to Vulcan to expose a conspiracy originating on Vulcan concerning arms-shipments deep into Romulan space. (ENT novel: Beneath the Raptor's Wing)
Ych'a and Denak were not released until 2158, after Silok was forced to resign from the V'Shar because of a scandal. Vulcan Administrator T'Pau released the two personally. (ENT - The Romulan War novel: To Brave the Storm)