Yicarin Yun was born in 2386 on the Trill homeworld as Yicarin Narra and is the twin sister of Aylema Daryn, formerly Aylema Narra.
The early lives of these sisters weren't very special. They lived a relatively 'easy' life getting ready for their eventual joining.
The joining changed the lives of the sisters completely.
While Yicarin received the good Yun symbiont, Aylema had the misfortune of receiving the Daryn symbiont, who turned out to have a rather dark and manipulative nature.
When the two sisters met some time after their joinings, their personalities had changed so much that they couldn't reconcile their differences, so they went their separate ways.
Yicarin joined the United Federation of Planets' Starfleet while Aylema felt more drawn to the Klingon Defense Force.
That's the last they heard of each other.
Life at Starfleet Academy was rather uneventful for Yicarin and she graduated from it with decent grades.
During her Academy years, Yicarin met Rachel Victoria Johnson and they became the best of friends, always ready to help each other out when they were in trouble.
Her relatively normal life ended when she was assigned to the Oracle class U.S.S. Kiseki, which was part of a task force sent to repel Borg invasion forces in the Vega system.
While she was helping out on the U.S.S. Khitomer, the senior staff on the U.S.S. Kiseki was killed by the Borg, leaving her as the highest ranking officer.
Eventually, the crisis at the Vega colony was contained and Yicarin was placed in command of the U.S.S. Kiseki by Admiral Jorel Quinn.
Following Vega, Yicarin was involved in many missions dealing with the Klingons, Romulans, True Way Cardassians and Jem'Hadar, Breen, Borg and even the Undine.
But the mission that changed her life the most was the one to the Burgus system, where she was ordered to investigate reports of Borg activity.
When the U.S.S. Kiseki arrived on the scene, she found herself arriving just in time to save several Romulan vessels from assimilation or destruction.
After liberating the I.R.W. Areinnye, Yicarin discovered that the Romulans had captured Borg technology.
Yicarin returned to the U.S.S. Kiseki after securing the Borg technology for herself.
However, a Borg armada was on its way to destroy both the U.S.S. Kiseki and the I.R.W. Areinnye.
The I.R.W. Areinnye was the first one to flee the scene after temporarily disabling the U.S.S. Kiseki with a complex viral matrix.
It did not take long for the Borg armada to arrive at the U.S.S. Kiseki's location and they opened fire just as the viral matrix wore off.
Yicarin and her crew fought valiantly, but the casualties were severe, with only four of the bridge officers surviving. Were it not for a mysterious ship coming to the rescue, the U.S.S. Kiseki would've been lost with all hands.
After the mysterious ship destroyed the Borg armada, it sent a cryptic message to the U.S.S. Kiseki.
"Look upon us, and tremble." After that, the Iconians opened fire.
Realizing that they were dealing with Iconians, the survivors said their final goodbyes and plotted a ramming course toward the Iconian ship.
Yicarin closed her eyes, waiting for the inevitable end...
It was an end that never came.
Right before the U.S.S. Kiseki collided with the Iconian ship, the U.S.S. Cutty Sark, captained by Queen Rachel Victoria Johnson, dropped out of warp and beamed the very few survivors aboard.
The U.S.S. Kiseki collided with the Iconian ship and exploded, severely weakening it. This allowed the U.S.S. Cutty Sark to destroy the Iconian ship.
Yicarin and the rest of the survivors were allowed to stay on the U.S.S. Cutty Sark until they were ready to be debriefed by Starfleet.
After the extended debriefing, both Yicarin and Johnson were promoted for their bravery, with Yicarin gaining the command of the U.S.S. Cutty Sark's new sister ship, U.S.S. Discovery.
And now, the close friends have been called to join Task Force Omega, formed by the Federation and the Klingons to take on the Borg together...