Jason Todd is a vigilante and the second Robin, making him the successor of Dick Grayson and the current partner of Batman. At the request of Bruce, he was taken under the care of Dick Grayson and became an official Titans affiliate.
Jason was born to Todd's father and Todd's mother who quickly neglected him and left him with his uncle Ray. His uncle frequently took him to bars but his uncle's drunken antics had them kicked out on multiple occasions. As a child, Jason read about the vigilante, Robin. Unfortunately, around 2012, Ray overdosed, leaving Jason to fend for himself. In and out of the foster-care system, Jason began committing petty theft, such as stealing hubcaps. At the age of eighteen, he attempted to steal the hubcaps off of the Batmobile but was stopped by Batman, who took him in and trained him as the new Robin.
Rescuing Dick Grayson
After a year in Gotham City, Bruce sent Jason to find Dick Grayson to warn him that members of Circus Haly's Circus were being systematically murdered. When Jason located Dick, he was in the midst of an ambush with soldiers from the Organization. Jason assisted Dick by taking down six armed soldiers, before helping Dick carry the body of Dr. Adamson to his car. While Jason expressed his passion for being the new robin they headed to a safe house. Before Dick could depart, Jason explained his true reason for being there, giving him files and autopsy reports that informed him on the death of his circus friends. Shortly afterward, they were joined by Dick's friends and he met Kory Anders, Rachel Roth, and Gar Logan for the first time.
Finding the location of the remaining circus survivor, Clayton Williams, Jason and Dick headed to Milwaukee, Wisconsin whee they attempted to enter a bar, in which Clayton worked. Although Dick was allowed inside, the bouncer automatically recognized Jason's ID as a fake and denied him entry. Despite being told to wait outside, Jason headed around the back and waited by the back door, sneaking in when someone exited to dispose of trash. As he entered, he flirted with some women and headed for the bar. He grabbed a stranger's drink and flirted with her, offering to buy her a new drink. However, her boyfriend took issue, causing Jason to pick a fight with him. Before it could escalate, Dick intervened, but there was an explosion that stunned everyone in the location. They exited the bar, where Dick received a call from Nick Zucco, revealing himself as the serial killer responsible for the deaths of the circus mates. Before Dick departed to resue a now kidnapped Clayton, Jason was given a brief speech on why he should not be Robin.
Despite this, Jason followed Dick anyhow and intervened in a fight between Dick and Zucco. Shot by an acid bullet, Jason made a remarkable recovery thanks to his suit's durable properties. Zucco was defeated and the police promptly arrived at the scene. Responding to reports of gunshots they were brutally beaten down by Jason. After severely attacking them, Jason was pulled aside by Dick, who took serious issue with his extreme violence, but Jason simply brushed it off and left, insulting Dick's identity crisis in the process.
Killing Dick Grayson
With Bruce out of the mansion for some time, Jason chose to entertain himself riding his motorbike indoors. He was interrupted by Dawn Granger and Hank Hall, who asked for his help to save Rachel and company. Once they arrived at the house, they met Donna Troy and Kory Anders there, who informed them about Rachel, her demonic father Trigon, and his plans to take over the world. Once granted access into the home, Jason was automatically taken into an illusion, in which Dick killed Batman. Enraged at the act, he and Dick battled it out. As a last resort, he grabbed a loaded, nearby gun—the same one that murdered Bruce's parents—and shot him straight through the head. This caused Jason to be instantly consumed by darkness and fall succumb Trigon's agenda.
Possessed alongside the others, including Dick Grayson, Jason was mind-controlled to lethally assault Gar. Ultimately, Rachel managed to defeat Trigon, causing all of the Titans to snap out of their possessed states. Bidding farewell to the others, Jason, along with Dick, Gar and Rachel headed to parts unknown. They made a quick stop at Bruce Wayne's, whereupon Bruce allowed them use of a tower so long as they took Jason. Arriving in San Francisco, they acquainted themselves with the old Titans' base of operations.
Being a Titan
Living in Titans Tower for the next three months, the newly-formed team began training tirelessly. Using Dick's suggestion of a blindfold, Jason and Gar sparred. However, Jason became annoyed when Gar properly hit him, leading to Dick stressing the importance of the exercise. That night, the team converged in the living room as helicopters flew past the tower. Turning on the news, they saw reports of a silver-haired girl, Rose Wilson, fleeing from police. With Jason impressed with her skills, Dick went to retrieve her, bringing her unconscious body to the tower to recuperate. Meanwhile, Jason highlighted how they did not know if they could trust her. Wanting to find out who she was, Jason and Gar took her old bandage and analyzed the blood, finding her identity to be that of Rose Wilson, the daughter of Deathstroke.
Todd (reprised by Walters) made a silent cameo in the Arrowverse crossover, Crisis on Infinite Earths, alongside Hawk/ Hank Hall (reprised by Alan Ritchson). The Titans Universe is confirmed to be Earth-9 which gets erased during the Crisis.
After the rebirth of the universe by Oliver Queen/ The Spectre, the universe got restored shown along with the archive footage of Titans including Todd.