"Every revolutionary ends up either by becoming an oppressor or a heretic."
Kamis, 8th Century Vulcan Reformist
Vulcan, a vassal state of the Terran Empire, was peppered with entire cities devoted to slave labor. Aris Met, the small city in which Kazak was born, was once such place. In exchange for working endlessly in the foundries of Aris Met, producing refined metals and alloys for the Empire, its people were granted a bare subsistence. Lorek and T'Laen, Kazak's parents, were both crucible-scrubbers in a duranium foundry. While using weak phaser torches to remove hardened metals and impurities from the ceramic pots in which molten metals were moved from one stage of the process to another, the two found love.
Growing up, as was common in these "service cities," Kazak was put to work at an early age. First with simple jobs that required little skill or understanding, and then to progressively more complex and strenuous jobs as he grew. He seldom saw his parents, only returning to their coffin of an apartment to sleep - and then sometimes only one day out or two or three. The Empire was particularly unkind to the children of slaves.
Kazak learned quickly that loners were soon consumed by Aris Met - either by bigger, stronger children or by the Overseers of the foundry. Aris Met didn't warrant even agonizers. Its inhabitants were disciplined "the old fashioned way" - with cudgels, fists, whips, and, if the offense was serious enough, execution. Kazak reasoned that the path to mere survival required surrounding himself with strength, and numbers had strength.
For a time, Kazak gathered other young people - first to aid him and later to serve him. They would steal food and supplies from the caste of slave-keepers and Terran logisticians, and recruited new members by giving them an ultimatum: join or be beaten. Eventually they realized that their masters didn't care whether slave children lived or died, and so the challenge became "join or die."
As Kazak grew to adulthood, his organization of militant and criminal children also grew and spread across Vulcan. Eventually, the Terran administrators could no longer simply tolerate him. Instead, they formed an allegience with him and he began directing his ranks to do their bidding. Not overtly, of course, to the rank-and-file gangsters it was just business as usual. To the Terrans, however, Kazak's organization made their job of quelling the Vulcan populace easier.
As a young adult, Kazak earned the attention of the Imperial military and was recruited for his leadership abilities and ruthlessness to the Naval Academy, where he excelled. During his time there, however, he got a taste of what it was like to be among the privileged elite - and the taste was bitter. The more he learned of the Terrans and their subtle, subversive intrigues, the less he liked.
Shortly before graduating, there was an incursion from the Prime Universe at the academy and Kazak ran into the intruders from "Star Fleet." He convinced them to aid in his escape from the Terran Empire and they brought him to Starfleet Academy where he studied and learned the ways of the Federation.
Ashamed of his history of violence and oppression, Kazak strove to be the best officer he could be, embracing fields of science and exploration, as well as the virtues of kindness and compassion. He graduated the Academy with honors and was soon afforded his own command. After commanding several ships and rising through the ranks, Kazak had earned the rank of Admiral.
As a culminating event, however, Starfleet tested him, asking that he prove his dedication to this universe by traveling to his own space-time and stealing a ship from the Terran Empire. With a small team of his most capable officers, Kazak went to the Terran Empire and infiltrated the Sol system shipyard. He stole the I.S.S. Relentless - a Galaxy-class Dreadnought waiting to be christened into the Imperial Navy.
Upon his return to the Prime Universe, he was granted the ship he stole to command and his choice of crew. Though ever flying in support of the United Federation of Planets, he insisted that his ship retain its I.S.S. designation and name - as a reminder of his past, and the hope that he and his ship could one day serve as an example, bringing the Empire into cultural and phiosophical alignment with the Federation.