Mercy Graves

Mercy Graves is a criminal, former Cadmus agent, Lex Luthor's former head of security at Luthor Corp and sister of Otis Graves. After Lex's arrest, Mercy went to work for his mother, Lillian Luthor, at Cadmus. After Lillian was arrested and Cadmus shut down, Mercy and her brother Otis began working for Agent Liberty.

Early life
In 1996, Mercy and her family went on a vacation to an unknown destination and she somehow dangerously injured her brother. So much in fact, that paramedics were called in an attempt to resuscitate him.

Working at Luthor Corp
At some point, Mercy became an acquaintance of the Luthor family and Mercy began work as Lex Luthor's head of security at Luthor Corp. After Lex was beaten and incarcerated by Superman, Mercy left her job.

Project Cadmus
After Lex's incarceration, Mercy and her brother, Otis, began working for Lex's mother, Lillian Luthor, at Project Cadmus. However, Lillian was also later arrested by Supergirl which caused Cadmus to be shut down.

Working for Agent Liberty
At some point after leaving Cadmus, Mercy and Otis met and began working for Agent Liberty. Under the orders of Liberty, the two ambused Dr. Rohan Vose outside his lab and proceeded to use lasers to slice off his spikes that stuck out of his arms in order to gain access to the lab. After Otis took one he took the other for playful reasons and Mercy criticised him for not acting professional. Just as the entrance to the lab opened, Supergirl smashed through a window but was deafened by a device used by Otis and had her legs handcuffed together by Mercy. Otis then shot her through a window at the end of the corridor and the two entered the lab. However, Supergirl managed to escape from the cuffs as Mercy found the package they were looking for. As the two prepared to leave, Supergirl flew back in but stayed behind in order to protect Dr. Vose from a bomb thrown down by Otis as the brother and sister made their escape. The two travelled back to Agent Liberty's lair and when Otis began playing with nunchucks, one of them hit something and Mercy threatened him not to do it again. When Liberty entered, Mercy told him their mission was successful but when Otis told him that Supergirl showed up she kicked him. Liberty then asked for the EMP and when shown it, he told then siblings to prepare for war.

Later, at President Marsdin's gathering for aliens, Mercy and Otis were instructed to attack it and after stealing uniforms from two D.E.O. agents, they threw the EMP which turned off all the lights in which the gathering was being hosted. Once inside, Mercy mudered an agent with a gun and attempted to kill Alex Danvers but was unlucky with every shot. She then threw down her gun and the two began fighting. Mercy quickly disarmed Alex and even managed to floor her, throwing a bomb once she was down and running away. The sibling then attempted to flee on motorcycles but were followed by Supergirl. Knowing she couldn't lose her, Mercy resorted to shooting Otis in the shoulder which caused him to fly of his vehicle and was sent plummeting down, forcing Supergirl to stop and rescue him. As she did so, Mercy managed to escape. Later, back at Liberty's lair, him and Mercy watched the news report of the reveal of President Marsdin being an alien. Liberty then complimented her on her work and she explained how much she loved her country. He then moved onto a woman he had taken hostage and killed her, explaining he was an agent of liberty.

Personality
In stark contrast to her brother, who is playful with his crimes and work, Mercy is very cool, calm and collected as shown when torturing Rohan Vose. When Otis was lasering Vose's spikes off his arms, he laughed and exclaimed that he was having fun whilst Mercy criticised him for acting like a child. During her conversion with Agent Liberty. she displayed her patriotic side as well as her beliefs of human supremacy.

Abilities

 * Peak human physical condition: As a former head of security and Cadmus agent, Mercy is in top physical condition after having undergone extensive training.
 * Expert Combatant/Martial Artist: As a formal Head of Security of Luthor Corp, Mercy is an expert in unarmed combat and martial artist. Mercy has proven to be skillful enough to match up against Alex Danvers, a highly skilled combatant in her own right.
 * Expert Markswoman: As a long time Head of Security, Mercy is an expert in firearms and was capable of shooting and killing an agent from an extended distance. She was also able to shoot her brother in the shoulder whilst they were both on motorcycles.

Season 4

 * "Fallout"
 * "Fallout"

Behind the scenes

 * In DC comics, Mercy Graves is the right-hand woman and assistant of Lex Luthor and aided him in most of his crimes.