Katherine (born Spade) is a pure-blooded Saiyan, born after the Saiyan Race was wished back into prosperity in Universe 7, she lived most of her early life on New Vegeta, before relocating to Earth to become part of the Earth Special Forces, and was eventually recruited into the Time Patrollers by Chronoa.
Kat is a young-looking, short Saiyan woman, with short black hair, and slightly tanned skin. She has blue eyes, and a small scar on the left side of her chin, which she received from Glacier. Her attire is based off of her mentor, Bardock, which she claims she saved up a "month's worth of zeni" to acquire all outfit pieces. She was also gifted attire based off of Future Trunks from the Goku Black Arc as a reward for completing her swordsmen training with Time Patrol Trunks, which she happily wore as a sign of respect.
A trait she has is that, unlike her brother, she retained her tail, despite numerous attempts to remove it, within a week it would always return, as such, attempts to remove it were halted, despite the great danger of her going Great Ape still persisted.
Like most pure-bloods, she is cocky, arrogant, easy to anger, and has a thirst for battle. She also has a rebellious side, as she frequently disobeys her brother's orders, and goes off into fights alone. She also openly mocked Glacier, a Freiza Race, who at the time had more than double her power level, knowing full well the Freiza couldn't do anything about it.
Her relationship with her brother Ace is rather strained, as stated, she frequently ignores his orders, despite being the leader of her Time Patrol unit, and the two argue constantly, steaming from the fact that Katherine moved to Earth despite their parents' wishes, and changed her name to better fit in with Earth society. When Kat finally turned not only Super Saiyan, but also showed off the fact she could go Full-Power Super Saiyan, Super Saiyan 2, and 3, she used this opportunity to boast to her older sibling, stating she was "Finally stronger than he could ever be." This was only strengthened when she achieved Super Saiyan 4 post a two-year training op with Mentor Vegeta in the Hyperbolic Time Chamber.
On the opposite end, her relationship with Verzwieflung, a Namekian is close-knit. The two met when Kat was still a child, where she was attacking bandits on New Namek, and was overwhelmed, Verzwieflung intervened, and taught the young Saiyan how to perform a Special Beam Cannon. Upon being recruited into the Time Patrollers, the two reconnected and became partners. Ace stated their partnership reminded him of Gohan and Piccolo. Their relationship was so strong, that when Ace put it up to a vote on who should lead the team upon his promotion, Kat was the first to nominate Verzwieflung, despite being multiple leagues above the Namek's power level.
Her relationship with Bardock started out rocky, as the young Saiyan would constantly mock the aging Saiyan, believing that he was nothing more than a Phantom like the other Mentors in Conton City, but when he revealed he was real like Future Gohan, her insults ceased, and she made it her mission to be a good student for the legendary Saiyan. Bardock taught Kat how to achieve the first three Super Saiyan transformations in order to combat Glacier, and personally showed her how to perform a Spirit Cannon, which became her signature move. Upon graduating his class, he gifted her a red bandanna similar to his.
Kat was born as Spade to Regis and Regina, and younger sister of Ace on the revived Planet Vegeta. Her formative years were spent in space, battling pirates, aliens, and other forms of warriors, as Regis wanted to show the galaxy not all Saiyans were evil. At the age of eight, the family landed on New Namek, where Kat went off on her own to chase down five escaping bandits. While fighting them, she was overwhelmed, and saved by Verzwieflung, a native Namekian outcasted for performing seven Fusions. The two became quick friends as the Namekian showed her several techniques before bidding farewell.
After returning home to Vegeta years later at the age of ten, Kat made her wishes to live on Earth known to her family, who promptly denied her request, as they found Earth was not suitable for Saiyans, despite Vegeta and Goku living there. Kat stole a Space Pod and ran to Earth, landing in West City, and was taken in by Bulma of Capsule Corporation. She changed her name to Katnip (later Katherine on suggestion by Bulma), and began training under Vegeta.
At the age of sixteen, she was approached by Chronoa with the offer to join the Time Patrol with her brother Ace, which she accepted as she'd found Earth life to be boring with no powerful enemies to fight.
Upon joining the Time Patrol, she was overwhelmed by the fact Ace had been deemed the "Hero of Time" after defeating Towa and Mira twice, along with the Majin, Dumplin. She now had a reputation to hold herself up to, and she used this drive in her training, learning as many moves, and becoming as strong as she possibly could with the end goal of beating Ace, and dethroning him from his high status. As time went on, she became more and more annoyed at the prospect of not being able to go Super Saiyan, as she found that was the only way she could possibly stand a chance against Ace. It was here that Glacier, a Frieza Race joined the unit, and the two quickly formed a rivalry. At first a typical Saiyan-Frieza feud, but turned heated as Glacier revealed his goal was to kill a Super Saiyan to prove he was better than his ancestor Frieza, to which Kat stated she'd never allow that to happen, despite her strained relationship with her brother.
The two frequently fought in sparing matches, always leading to a draw due to Glacier using lethal techniques, outlawed during sparing matches. It got to the point where Ace had to physically save Kat from death by going Super Saiyan and beating Glacier into unconsciousness. Kat, enraged by this, attempted to attack Ace, who then suspended Kat from Time Patrol duty, and instead put her on Milk Delivery for six weeks. It was during this time, Bardock and Future Gohan came to Conton thanks to Ace's efforts. Kat took Bardock as her new mentor, assuming him to be a phantom like the other mentors, she was delighted to find out he was the real deal, and begged to be taught how to go Super Saiyan. The Saiyan agreed, taking Kat to the Hyperbolic Time Chamber, and showed her a vision of Glacier killing Verzwieflung, which enraged her to the point where she finally went Super Saiyan. Bardock, pleased with this outcome, took her even further until she could go Super Saiyan 3 with little effort.
Kat kept the charade of not being able to achieve Super Saiyan a secret, until Glacier was restored to the Time Patrol, and challenged him to a duel with lethal restraints removed. Glacier, taking this as nothing more than Saiyan pride accepted, and Katherine faked losing the fight, before locking Glacier in a head lock and stating "You wanna see something cool!?" and revealed she could go Super Saiyan, promptly, she defeated the Frieza race easily, she readied a Big Bang Attack. However, she chose to spare the Frieza, she powered down and claimed, "No matter where you go, no matter what you do, you will always remember, a filthy Saiyan was the one who brought you to a crying child begging for his life." and left the scene, much to Ace's shock, and Bardock's approval.
Her membership within the unit restored, she along with Verzwieflung would perform dozens of Patrols together, defeating enemies such as Cell, the Androids, and going toe-to-toe with Broly. It was during this time that Glacier left the team, citing his failure to defeat Katherine destroyed his honor. Kat saw him off, mocking him one final time, stating that he was an even "bigger failure than Frieza ever could be" as Frieza at least temporarily killed Super Saiyan Blue Goku.
Invasion of Conton
Years later, Kat had been promoted to Captain Time Patroller, Glacier, now Supreme Commander of Time Distorted Galactic Frieza Army, broke the time barrier of Conton City, and began slaughtering Time Patrollers. It was here, Glacier revealed he achieved Golden Form, and easily dispatched Katherine, Ace, and Dumplin, only being sent away by Chronoa using the Conton City Dragon Balls to wish him away. She revealed her wish was only a temporary fix, as Glacier would find another way to break the barrier. Kat, enraged by her quick loss to the Frieza Race, ran off to the present time, Age 790 and asked present-day Vegeta to teach her how to go Super Saiyan 4, which Vegeta agreed to, and took Katherine to the Time Chamber with several Blutz Wave Generators. She then spent a year and a half in the chamber with the Saiyan Prince until she could not only go Super Saiyan 4, but keep the transformation.
Upon return to Conton, she found the city under ransack by both Glacier, and a Supervillain Broly. Instead of goading Glacier into a false sense of security, she chose to directly go Super Saiyan 4, and with the help of Ace, and Verzwieflung, the trio fought Broly back to a point where Dumplin could sent the brute to the Demon Realm, and Katherine defeated Glacier with a single Big Bang Kamehameha.