Trista was born on Revolur, a planet that was founded by her grandfather during the reunion of the United Universes, and defended it well against the Villain League and the Darkspawn during the Second Cartoonian War. When the war ended with Oogway banishing Lord Cobra away, by 2009, the year the Shell Lodgers were born, Trista was a young adult who had dreams to be like her grandfather. But she was always told that she wasn't ready to take the risk of exploring the UUniverses. But still, she played waiting for her future and training herself to handle danger alone well. But one day, she pushed it too far by taking a joyride into space and, after getting sucked into a black hole portal, and became stranded on a world called Mystor, as she felt that the days of crusading were over and she had nothing left to do in her time.
Mystor was a world that was grim and dark, but also whimsical and Disney-esque. She spent time living in this new world after being rescued in the crash by a socially-awkward rookie wizard elf named Constantine, who never got the chance to go crusading in the UUniversal Crusades himself because his overprotective parents forbidden it after getting scared by the Second Cartoonian War. She related to his struggle, and laughed when he said she was pretty on impulse, especially since her clothes were close to falling off due to damage. They became friends and Constantine taught her how to do magic. Later in their years, Trista accidentally stumbled upon the skeleton of a Keyblade Wielder, and obtained his Keyblade, which was one of the strongest, called the 'Sense of Adventure', taking it with a promise to the warrior's grave that she would use it for more than he would've in his lifetime.
With this new weapon at hand, she defended Constantine's village from marauding orcs, as her magic was in sync with her weapon. She even used it to weave her current attire, which Constantine complimented. However, she realized too late that the original wielder of her Keyblade had one remaining enemy: Otsuka the Tombstone, a golem of unimaginable magic capabilities who wanted the power of the Sense of Adventure, and came to Trista out of desperation since he was dying as his magic was impure, and thus so was his magic youth, claiming that dark magic could taint and was destroying his body thanks to a curse, seeing the Sense of Adventure as the only thing that can save him, which is what he was ultimately looking for after the death of Thai, the Keyblade's original wielder. He stole the Keyblade with little effort and injured Trista, and she was even exiled by her own people blaming her for Otsuka's destruction of their town. Constantine even defended her and disobeyed his parents to join her, and they had to stop Otsuka before he corrupted the Sense of Adventure forever.
After taming a unicorn and naming it Amalthea after Trista's favorite movie and inspiration, Rankin-Bass's The Last Unicorn, she fought against Otsuka's forces for a year until she realized she was too late to save the Sense of Adventure from corruption. Enraged, she attacked Otsuka but lost Amalthea in the process and Constantine was fatally injured. She executed Otsuka by using his sword and wand, and grieved over the death of Constantine. But she realized that unicorn blood was a remedy when Amalthea's blood touched Constantine and her, resurrecting him and rejuvenating her, and allowed her to bring the Sense of Adventure back to the light. The blood even maximized their lifespan and allowed them both to live to be 600. After this, Constantine and Trista confessed their love for each other and rebuilt her ship into a Gummi Ship to elope in the sea of stars, after finding out that Constantine's parents died while they were away.