The Flying Graysons were the parents of Dick Grayson later known as Robin. Their names were Mary and John Grayson. They were a family of circus acrobats.
While preparing for a performance, Dick overhears Tony Zucco, a gangster, attempting to extort protection money from the circus owner. The owner refuses, so Tony Zucco sabotages the trapeze wires with acid. During the next performance, the trapeze from which Dick's parents are swinging snaps, sending them to their deaths. At the performance, Bruce Wayne is in the audience. Bruce then asks Commissioner Gordan if he has any family close by to which the answer was no. Bruce Wayne decides that Dick would be better off with him than in a foster home. After Dick was adopted Bruce spent his nights looking for Zucco after getting a lead from his new son about what happened that day. Eventually, Bruce finds out that Dick is feeling lonely and he recounts his own feelings of loneliness after his parents had died. Thus, after extensive training, Dick becomes Robin. They start by disrupting Zucco's gambling and extortion rackets. They then successfully bait the riled Zucco into visiting a construction site, where they capture him. After a falling out, Robin left his mentor's shadow and went to Jump City to be his own hero, only then to be the leader of the Teen Titans.
However, Robin would not let go of his past forever, as seen in Teen Titans Go! #47. It was a sad day for Robin, as it was the anniversary of his parents' death, and he had been close to crying for the whole story. Batman narrates the story, stating what he and Robin had been through together, stating that they were a "family act." Each Titan tries to cheer Robin up, Cyborg does a workout routine, Beast Boy tells him jokes, and later pulls a prank, and finally, Raven offers emotional healing as she looks at Robin's tragic memory in the episode, "Haunted". Starfire later goes onto the pier, seeing Robin without his mask on, crying. She comforts him, allowing him to vent. Later he says that she helps him remember there's more to life than fighting crime. Unknown to Robin, his adoptive father/mentor was watching from a distance. At the end of the story, they kiss, much to Batman's happiness, knowing that Robin has grown up, and he will be fine with Starfire.