- For her primary universe counterpart, see Kayl.
Kayl was a part of the Terran Rebellion in 2375, and joined the advanced starship Phoenix-X. Throughout her time with the rebellion, she had proved herself a competent and skilled fighter. It's these skills that allowed her to be chosen as one of few who would crew Smiley's secret starship, Phoenix-X. (Star Trek: Phoenix-X)
During the only month the Phoenix-X was in service, Kayl lead the Operations department. Her skills were vital aboard the ship, especially during the crew's final encounter: after only a month of service, the Phoenix-X encountered an Iso-Star. The star forced the ship and crew into the primary universe, where they were confronted with an identical ship of the same name and crew.
After a furious battle, Kayl and her crew were destroyed. It wasn't until eight years later that the crew would be revived by a young omnipotent being. Back to life, in the year 2383, Kayl and her crew mates abducted the first starship they could find - a USS Fusion.
Now with life returning to normal, Kayl was able to focus back on her career. Unfortunately, her conscious played on her mind harder than ever before - because in order to acquire the ship, the entire Starfleet crew had to be killed.
When Captain Daniel made the decision to mass-murder yet another crew of another ship, Kayl decided to stand up for what she believed in. She stepped before her Captain, aiming a phaser, and told him that what he was doing was wrong. Luckily, her crew stood behind her cause in this, and before any furthering on the subject was possible, the Captain found himself incapacitated by an energy surge from nearby circuitry.
Meanwhile, the omnipotent being, known as Rein sent the ship and crew into the Mirror Universe in order to fix things. Being back, and having the Captain out, prompted Klingon-Cardassian Alliance sympathizers aboard the ship to take action and take control. Before Kayl knew it, she was one of the captured. She returned to Alliance space with the rest of the captured Terrans, most likely to become slaves again. ("Pure Evil", "Mirrorlyness!", "Broken Pieces")