Born from a tale of passionate sin, the twins Takumi and Natsumi were the children of first cousins Atsushi and Akiko of the noble Tokugawa clan set in Capital Island. The Tokugawa clan was a lineage of successful war generals who soon allied with The Syndicate and expanded to underground businesses (firearms & casinos); and with no other successors, their elder, through much persuasion had permitted the forbidden union.
Ever since birth, the two children were inseparable. For the first six years, they ate, bath, and slept together like any other innocent pair of siblings. Their parents had loved and spoiled the two, raising them to believe they were only second to the fire lord's family.
In their last year together, the two had discovered their powers. When the child of a rival family challenged the two's authority in school, Natsumi was no more merciful than Lord Ozai himself, scortching the young child's neck. When the opposing female attempted to burn Natsumi's hair, Takumi swiftly blocked her flames with his own.
Of course, happiness never lasts. The children were reprimanded; however, due to their influence, they were encouraged to change academies, and their parents agreed it was a good opporunity to start their trainings early.
At the age of six, the twins were given an illusion of choice to decide their future careers. While Takumi would first be a war general with brains and brawns, Natsumi was to be a proper Tokugawa lady -- a prim beauty in social gatherings but a demon in the front lines of war. For the next eight years, the kids were thrown into different elite schools; however, like before, they had easily claimed titles of king and queen respectively.
Once the twins were thirteen, Takumi had received a letter from his parents about his engagement to the Sanada family; thus, after graduation, he, not possibly caring any less, sailed home and waited for his parents who had been in the Earth Republic. Meanwhile, Natsumi was instructed to meet the male Sanada, who was her future lover.
Upon reaching home, he had accidentally caught an exquisite sight: a bathing female. The young lad, for the first time in his life, had found himself utterly speechless as if he were lured into a wonderland. Not recognizing each other, the twins interacted minimally; however, from how Sanada had trained and Takumi had debated, they both felt each other's presence. Two weeks later, the pair of firebenders were shocked to discovered that their crush was not their fiances but actually their own twin. With heavy hearts, the two suppressed their feelings for each other.
Due to the pre-exisiting incest in their family, the twin's parents had a hunch about the two's feelings for each other, announcing that they will soon be married off to other families for political reasons. For the next six years, Takumi and Natsumi's repressed emotions had allowed them to grow hatred towards their parents. Under the fake but convicing notion that they were tired of being Tokugawa pawns, the heirs fled to different areas of the Fire Nation --- only to be chased after by different members of the Syndicate, who found it favorable to please Atsushi. Finally, they had heard of a group of slaves discussing about Kyuseishu, an organization dedicated to destroying the Syndicate.
As a form of rebellion, Takumi and Natsumi rode a ship and fled to Republic City. They secretly knew the new city was in favor of their interests: bloodlust, unknown incest, and protection from the Syndicate; they knew they had a new start. With the two's capabilities, Takumi and Natsumi were easily financed by one of Republic City's crime gangs as both brains and brawns respectively.