The folks at Gotham are persistent. Despite the Fox series taking place years before Batman shows up in Gotham City, they’re insistent on including as many characters from the Batman lore as possible, whether they’re future allies or eventual antagonists. There are a few cases where a character can’t directly appear, but that isn’t stopping the writers from referencing them to the best of their ability, which is what will be happening at some point with Batman’s famous sidekick Robin.
Recently, showrunner Bruno Heller confirmed to Entertainment Weekly that since Bruce Wayne is still a a teenager, Dick Grayson hasn’t been born yet. However, the show will still reference the future Boy Wonder in what he calls a “prenatal origin story.”
“We’re going to do a prenatal origin story for Robin down the line... There are no MRIs involved. There’s an episode coming up where we learn how Robin’s parents got together.”
In the comics, Dick’s parents are John and Mary Grayson, who become acrobats for the traveling Haly’s Circus. Dick follows in his family's footsteps, and together they make The Flying Graysons trio.
After a disagreement with the circus manager, gangsters take their revenge by sabotaging the swinging wires, causing Dick’s parents to fall to their deaths while performing their act. Bruce is in the audience when this happens, and seeing a kindred spirit in the boy, he takes Dick into his care and trains him to become Robin, wanting to give him the direction that he never had at that age.
Ben McKenzie previously mentioned that the Graysons would show up, but he didn’t specify whether Dick would be involved. Thankfully Gotham isn’t doing anything drastic like making Dick the same age as Bruce. The show has no qualms with playing around with how old its characters are (as seen this week with Harvey Dent), but I don't think there can be any compromises when it comes to the age gap between Bruce and Dick. In order for their particular mentor/mentee relationship to work, Bruce has to be well into adulthood before he takes Dick under his wing. It can’t work if the two of them are the same age of if Bruce is only slightly older.
As for Dick’s parents, they haven’t appeared too often in the comics outside of the role they play in Dick’s origin, so it will be interesting to see how Gotham weaves them into the narrative. It’s easy enough to include characters that have ties to the police department, government or organized crime, but these two are circus performers, or at least they will be. Falcone’s power stretches far, so he may have ties to Haly’s Circus, and John and Mary may somehow get entangled in criminal shenanigans. Another possibility is Gordon somehow interacts with them in his off-time, and they could be among the few people in the city not directly involved with all the madness. Their inclusion may also lead to the introduction of Tony Zucco, the gangster who ordered the Graysons’ murder in the comics. We alread have Falcone and Sal Maroni, why not introduce the third most famous Batman Italian gangster?