The gang used to be her family, back when everything made sense. There was a structure, an order, and everyone knew their place. The oyabun kept the soldiers in line and they did what they were told, not simply out of fear of failure but also because they deeply understood that the success of the entire organization relied on the performance of its foot soldiers. Growing up had been violent but fair, and she did well.
Only as she got older did she see the grim reality of her situation – the powerful made their fortunes and paid for their excesses on the backs of the lower-class, same as in any corporation. They weren’t her family, they were her wardens, keeping her and her fellow soldiers locked into an endless cycle of systematic control. She knew she had to leave, but knew that doing so was almost certainly a death sentence. Either way, the old her would be gone.
Compounding her decision was the fact that her best friend had already seen the truth of their situation, and embraced it. They were going to climb to the top, seeing power and prestige as goals in and of themselves. She knew they were ruthless, but it had never hit them before that moment just how bloodthirsty and power-mad they had become. She told her lover, expecting them to come with her, or at least to see things as she did.
It was all they could do, her lover said, to keep the clan from killing her if she tried to make an exit. Her lover saw the reality of the situation, that inside the clan was no better or worse than anywhere else, but there they had made a life, and an arguably good one. And of course there were the complications of the best friend. She gave her lover a simple black-and-white option: to meet her and escape, risking death but striving for freedom, or stay home in the cruel certainty of their old life.
The internal conflict happening at the highest, international levels of their organization gave her the opportunity to make her escape, but when the time came, his lover was nowhere to be seen. Fearing the worst, she ran, thoughts of freedom and vengeance taking her far away from the only life, and people, she had ever known.
This concept draws heavily from the Cowboy Bebop character Spike Spiegel, but hopefully gives enough freedom and flexibility to be used for almost any former member of organized crime with a dark past, and perhaps allies or enemies chasing after them.