Between 2012 and 2017, Gary was employed by the Time Bureau. In late 2017, after Julius Caesar was displaced in time, Gary and another agent were sent to retrieve him. Once they got there, they were knocked over by Mick Rory, who was chasing Caesar. Rory tackled what appeared to be Caesar, and the time agents brought them back to the Time Bureau. However, they quickly realized that Caesar was simply a partier. Gary showed them out, validating their parking.
Following that, after the Legends stole the Waverider, Agent Ava Sharpe had Gary follow them to Wisconsin in 1870. They quickly caught on and took Gary as a prisoner aboard their ship, admitting that he had been sent as a spy. When Agent Sharpe checked in with Gary, he attempted to convince her that everything was fine, while in fact, being held at gunpoint by Sara. Sharpe soon came aboard, and, following a brief altercation with the Legends, freed Gary.
Shortly after, Gary was sent to fix an anachronism in Seattle in 2042. He watched as Kuasa used hydrokinesis to stop an A.R.G.U.S. transport vehicle, nearly catching its prisoner, Zari Tomaz. Green sent a distress call to the Time Bureau. The call was intercepted by the Legends, who sought out Gary. They attempted to find out what had happened, but Gary refused to tell them, until Mick intervened and threatened him, so he opened up. He followed them back to the Waverider, staying there until they brought Zari aboard. Having not technically prevented the anachronism, as was Agent Green's initial mission, he scolded them. Soon after, the Time Bureau caught up with the Legends, allowing Gary to transport himself aboard their ship, assisting Agent Sharpe with talking with the Legends.
When Zari had to be put under sedation to heal herself from being coated with volatile time fluid, Gary appeared in a mental simulation that had him transport to the Waverider to warn the Legends about a bomb being planted on their ship. He tried to teleport to the ship but ended up stuck inside the trash compactor. He couldn't warn the team so he used a chrono repeater to make the final hour before the bomb's detonation repeat constantly to give the team the time they needed to save themselves.
When he was found, Mick Rory took the repeater from him and destroyed it as he thought it was the bomb. He explained what happened and found that there were only five minutes left before the bomb exploded and it was their final chance. They found the bomb that was planted by Damien Darhk and Zari took it and isolated herself to save the team and the simulation ended when the bomb was supposed to blow. When Zari woke up and learned the truth, she wondered why Gideon had put Gary in the trash compactor the whole time, to which Gideon replied that she thought it would be funny.
When a fellow employee named McNeil, who Gary didn't like, had been given top honors, Gary called him and told him that he deserved it and that the bureau was lucky to have him. After he hung up, Gary vowed that he would 'come for him'. A moment later, Wally West had sped over to him and took his time courier and pants, leaving him out in the middle of the street. Gary quickly moved to get away and inform Ava Sharpe, who was on a date with Sara Lance. When he got there, he quickly told Ava what happened and also told her that there was a report that Rip's brown trench coat had been stolen from the bureau's vault. He then commented that Ava looked amazing but she told him to back off as she went to alert Sara. However, they came back to find that Sara had left, just as dessert came. Gary said that what she did was harsh and asked if Ava wanted him to have the dessert boxed for her but Ava told him to be quiet.
Gary had been at the Time Bureau when a Palmer tech smart watch appeared with a message from Ray Palmer. He had alerted the Waverider and was surprised to see that Ava Sharpe was there with them. He played the message which had Ray tell them that he was a prisoner of Damien and Nora Darhk and to not look for him as they would kill him if they tried.
Gary had gone with Ava Sharpe to New York in order to find John Constantine when Sara Lance had been taken by Mallus and the Death Totem. After going through his file, Gary realized that Constantine was a warlock and told Ava that he himself was a Level 9 warlock but she told him that Dungeons & Dragons didn't count. They found him trying to give a ritual service to a woman that wanted her son to be married. They revealed the situation and Constantine told them that the Death Totem was linked to Mallus as the lost tribe of Zambesi to which it belonged had sided with Mallus during his war against the other five tribes. He revealed that he could get to Sara through Mallus' realm because they had a metaphysical connection, and Ava revealed that she also shared a strong connection with Sara and Gary realized that the both of them had slept with Sara. Constantine tried to bring both himself and Ava into Mallus' realm but the demon blocked him and released a burst that sent all three of them flying.
After they had failed to get to Sara, Gary proposed a different approach. He first told the story of reclaiming a lost weapon in his Dungeons & Dragons quest and Constantine realized that they didn't have to get to Sara but get to the Death Totem. The warlock excitedly kissed Gary and set out to take them to the totem itself which would bring them to the Waverider and to Sara. They succeeded and Gary watched as Constantine tried to subdue Mallus and exorcise him from Sara. However, the demon went and used Astra's voice to weaken his resolve before sending both Gary and Ava flying off to keep them from interfering. After Sara had been saved, Gary went with Constantine back to New York where he got him to become a fellow Dungeons & Dragons player by swearing on a twenty-sided die.
When Ava hadn't appeared at work in days, Gary became worried and went to the Legends to try to find her. He came upon Sara Lance and Ray Palmer and he informed them about Ava and he also learned that she and Sara had broken up, to his disappointment. He brought them to the Time Bureau where they went into her office to find some clue about where she had gone. To his surprise, they learned that Ava's personnel file had been erased. However, they found postcards in the trash that were from her parents and they lived in Fresno. They believed that she might have gone there to try and get over her and Sara's breakup. When they got there, Sara quickly deduced something was wrong and it was revealed that Ava's parents were in fact actors that were hired to be a convincing backstory.
They returned to the Time Bureau and found that Ava had returned though she said that she had taken the time to visit her parents in Fresno, which they knew to be untrue. Sara then stole her time courier and they hacked its history when they found that Ava's first mission had been to Vancouver in 2213, which Gary had informed them was a no-fly zone. He explained that time couriers and the Waverider couldn't fly there and only a Time Bureau director could make that kind of authorization, or the Mother Ship could take them there. He explained that he failed his flight test but Sara told him that she would be flying. They arrived in 2213 and quickly found themselves surrounded in Ava Sharpe look-alikes. They found out that they were clones that were created at the AVA Corporation. Gary was amazed by all the Ava's running around while Sara Lance was horrified.
He followed Sara and Ray to the AVA Corporation where they found that the Ava clones were made from the best genes gathered in the attempt to create the perfect woman. They believed that Ava had made the time a no-fly zone to keep people from finding out the truth about her but when Ava appeared, after tracking the stolen Mother Ship down, she fainted at the sight of the clones. It was then that they realized that Ava had no idea of the truth behind her origin and Gary offered to mind wipe her but Sara told him that she deserved to know the truth. However, the clones found them and declared them trespassers and tried to execute them but they all fought them off, while the one that Gary did try to fight turned out to be the real Ava, who twisted his arm. Back on the Waverider, Gary became depressed after everything that happened and Ray took him aside as he offered to mind wipe him of what he had seen in 2213.
Due to the Legends latest blunder, Gary teamed up with the warlock Constantine to take down mystical creatures. During this time Gary and Constantine did "a thing" that Gary thought made him lose his virginity. This wasn't the case.
Gary later approached the Legends dressed as Constantine, before the real Constantine showed up, carrying a dragon's head. The demonologist demanded to know whose idea it was to release Mallus, in which everyone points to Sara. Constantine then reveals that Mallus wasn't the only evil locked away in the time prison.
For the most part, Gary is a loyal agent of the Time Bureau, more than keen to carry out his mission. However, he is susceptible to threats, particularly those involving injury or death. Gary is not the bravest, but he does what he can to support those who he knows can save the day. He is often the butt of jokes, from his coworkers and from the Legends, but he doesn't let any of it get to him, and continues being cheerful. Gary is very awkward and excitable around people which tends to make himself get passed off as annoying. He tends to go on long, meandering, info-dumps that would have a point if the majority of people didn't cut him off. Mick refers to him as the 'Time Dweeb'. He is tentative and a bit fearful around the Legends at first, possibly from being beaten up on somewhat by Captain Sara Lance. However, as season 3 goes on, he is shown working together with them more fondly and even "shipped" his boss with Sara Lance.
- Time courier: Gary carries a time courier. This device allows him to transport through time and space without the need of a timeship. It has been stolen twice by Wally West and Sara Lance respectively.
- Gary claims to be a level 9 warlock in Dungeons & Dragons.
- Gary has poor circulation.
- Gary is very proud of the fact that he lost a nipple to a unicorn.
- Gary is the 12th character in the Arrowverse to have an episode named after him in a civilian sense in some way, after Sara Lance, Felicity Smoak, Harrison Wells, Oliver Queen, Alex Danvers, Zari Tomaz, Harry Wells, Iris West, Winn Schott, Ava Sharpe and Nora West-Allen.
- Gary has a fear of things covered in sheets.
- Gary is the second openly bisexual male character on the show. He had a crush on Ava for a while until being shot with a flash gun by Ray Palmer, and he had some sort of relationship with John Constantine until the latter "let him down easy". He also attempted to flirt with Mona but was unsuccessful.
- Ironically, his ex-lover Constantine is the first.
- Despite being 6 feet tall, Gary is the second shortest major male character in season 4, tied with Nate Heywood. Hank is 6'3", Ray is 6'2", and Mick is 6'1". The only major male character shorter than Gary this season is Constantine at 5'11".
- Gary seems to have a close friendship with Ava. According to Ava, he excitedly told her about his nipple soon after defeating the unicorn. He is also Ava's copilot on her timeship.
- Gary has also bonded somewhat with Nate and considers him his "time bro".
DC's Legends of Tomorrow