Barry Allen - Injustice: Gods Among Us: Arcade Ending: The Flash

The alter-ego of The Flash, Barry Allen was haunted by his involvement in the rise of the One-Earth Regime, enabling Superman, the High Councilor to commit cruel atrocities without any pushback or protest. 

After dethroning and detaining the Kryptonian tyrant, he helped smash the Regime's hold over the planet, before finally going into exile.  There he remained, wracked with guilt and shame, unsure how he could atone for his crimes. 

Barry would do all he could to keep Central City safe, although would take no credit, nor show his face for fear of opening old wounds. He would earn the new nickname, "The Ghost", an alias he would take on, now that The Flash and his legacy were hated and reviled for all the pain and death he and the Regime had caused. 

The Flash - Injustice: Gods Among Us: Arcade Ending: The Flash

A former member of both the Justice League and the One-Earth Regime, The Flash rebelled against his friends and allies, realising that they had become too focused on maintaining order at any cost, even the lives of innocent people. 

Defeating Superman and sending him to the Phantom Zone, The Flash helped dismantle the rest of the Regime, before going into a life of self-exile and permanently giving up the mantle of The Flash. 

Or so he thought. 

His desire to help others in need was too great, and, in the dead of night, he would use his superspeed to quickly take out criminals before vanishing again, so as not to let people see who he was. 

While some were able to piece together his identity from eyewitness accounts of a red blur, others would just be grateful that someone was looking out for them, dubbing him "The Ghost." Satisfied with the moniker, The Flash did not bother to correct them, choosing instead to take on the name and cast aside his old name and legacy, which had been forever tainted by the blood, pain, and fear of all the Regime's victims.

"The Ghost" - Injustice: Gods Among Us: Arcade Ending: The Flash

With the One-Earth Regime broken and leaderless, now that Superman had been banished to the Phantom Zone, The Flash was left with two choices; to atone for all the atrocities he had committed as a member of the Regime, or go into hiding, as many of his former allies had done. He chose the latter, exiling himself from the public eye in an attempt to outrun his past.  

Yet Barry quickly found he could not stand by and let injustice run rampant in Central City while he had the power to stop it. Using his super-speed, he would zip in and out of crime scenes, before disappearing without a trace. 

Eyewitnesses to his actions would report seeing a red blur, leaving some to deduce his true identity. 

However, to others, he would simply be known as "The Ghost," earning respect and gratitude from the citizens of his hometown.

While these actions could in no way rewrite the sins of his past, he felt it was at least the start of his atonement.

The New Titans - Injustice: Gods Among Us: Arcade Ending: Deathstroke

Following the fall of Superman's One Earth Regime, The Elite, loyal paratroopers who had committed countless atrocities in the High Councillor's name, went into hiding, fearing retribution and sentencing as terrorists and war criminals. 

While they had successfully managed to remain off the grid, avoiding detection from newly assembled governments, they could not hide from Deathstroke.

Wilson, impressed by their reputation, sought them out, offering them a chance to train under him and use their skills as political assassins. Leaping at the opportunity they agreed, becoming the New Titans. 

With Deathstroke as their leader, they have executed covert operations to influence global affairs.

Deathstroke - Injustice: Gods Among Us: Arcade Ending: Deathstroke

Responsible for overthrowing the High Councillor from his position of power, Deathstroke capitalised on the political vacuum created by the downfall of Superman's Regime. As new governments emerged, they became new clients for Deathstroke, leading to a surge in his business. His services ranged from executing assassinations, assisting revolutions, to inciting unrest. The demand for his services grew to such an extent that he could no longer operate alone.

In the aftermath of the One Earth Regime's reign, their Elite Troopers, who had committed atrocities in Superman's name, were forced into hiding due to public outrage and a desire for retribution. While they were elusive to most, Deathstroke was able to locate them. He recruited these outcasts and formed a group known as the New Titans. 

This group quickly established itself as the world's leading political assassins. Deathstroke's strategic recruitment of the renegade Elite Troopers not only expanded his operational capacity but also solidified his position as the greatest mercenary in the new world order.