Rhonda Pineda was created by writer Geoff Johns, with her first making an appearance in DC's The New 52 FCBD Special Edition in 2012, though not properly introducing her until the next year in Justice League #18.
Major Story Arcs
Joining the Justice League
Rhonda Pineda begins to assist the Justice League during Throne of Atlantis, when the Atlanteans invade the surface world, lead by Aquaman's brother Ocean Master. Rhonda is one of the many heroes to answer the call for assistance, though no one notices her due to her size, yet she plays a key roll in disarming the bombs that would have sunk Boston into the Atlantic Ocean. She later comes to the League's attention when they invite would-be membership candidates to their Satellite, as she makes her presence known after assisting in disabling a malfunctioning Platinum and capturing her value resonmeter. She is a student at Ivy University.
It is later revealed after a battle with Despero that she is an agent for Amanda Waller, who gave her the Atom Suit. She is intended to be the counter to Element Woman, however she is showing a dislike for her choice. She was placed on the team to infiltrate and spy on her new teammates Firestorm and Element Woman and how to render their respective powers from helping the league in battle. She is the only person who is aware of an impending war. Her picture is also placed next to Element Woman's, showing that Atom is the perfect match to defeat her.
It has been revealed that that Rhonda is actually from the Earth 3, the home of the Crime Syndicate. She worked with the The Outsider to frame Superman for the murder of Arthur Light by going into Superman's brain and using a sliver of Kryptonite from Batman Ring to hit a nerve and trigger his heat vision. This is also what was subsequently weakening Clark Kent throughout the storyarcstory article. It was reveled the she told Cyborg form the Justice League that she was a spy on the team and she told him that she was the one to go into Superman ear drum and in to his nerve system to attack the nerves and set off his heat vision to kill Dr. Light. Cyborg was going to tell the team and it was also reveled that Cyborg is also a trader to the Justice League his body was badly damage by Atomica and he turned in to a super villain Mentalo. The Justice League and Justice League of America where in shock to hear all this happing by Atomica to get the Earth- 3 hero villains to attack Earth-1 hero's and they will form her help take over the world.
From what is seen so far and described by Cyborg, Rhonda is a shy but heroic young girl. She has been shown to use her powers for the purpose of going into video games.
She is also shows regret for her loyalty to Amanda Waller, even willing to give her suit up for it. She truly wants to be a hero.