It’s Dick Grayson. The laughter and happier demeanour is very much Dick, but the costume is based on the one designed by Neal Adam’s for Dick’s second successor (Tim Drake). It was Batman: The New Adventures which took that costume and removed the green to give the yellow/red/black version. Robin’s throwing discs are like those used by the Robin from Glen Murakami’s Teen Titans cartoon. The entire laughing from the shadows thing really reminds me of the Shadow.

At SDCC Greg Weisman described Robin as:

This is Dick Grayson, aged 13. He’s the youngest member of the group, but he’s also the guy with the most experience. He’s been doing this since he was 9-years old so he’s been doing it four years. He’s the guy with all the chops.

Robin is voiced by ex-boy band singer Jesse McCartney who described his character to CBR as a “prepubescent, cocky little kid” who ends up becoming the leader of the team.

When he was nine-years old Dick Grayson became Robin and entered a world that few people ever experience. We haven’t seen his origin on-screen, but we can assume, based on the original comics chronicles, that Dick Grayson’s family were the “Flying Grayson”, trapeze artists who were assassinated by a criminal who was trying to extort money out of the circus they worked for. Bruce Wayne (alias the Batman) witnessed the Grayson’s murder and instantly identified with their orphaned son. He took the grieving Grayson in and trained him to his sidekick and partner in crime fighting. For four-years Robin worked alongside the Batman until the day that he and three other sidekicks were told that they were to be inducted into the Justice League.

On July 4th Robin, Aqualad, Speedy, and Kid Flash (Robin’s best friend) were brought by their mentors to the Justice League’s Hall of Justice. They were given a tour, but that was it. Speedy was furious and revealed that Hall wasn’t even the League’s real headquarters – it was a false front designed to deflect attention from their real HQ in orbit. He accused the League of not treating them like equals and then stormed out. Robin hadn’t expect anything more than the tour, but Speedy’s parting words stung “I guess they’re right about you, you’re not ready.”

Immediately afterwards the League received two emergency calls – one to a fire at Cadmus Labs and another to a supervillain attack by Wotan. The League were forced to ignore Cadmus and left to fight Wotan. The sidekicks were told to stay put, but Robin knew that Batman had his suspicions about Cadmus and suggested to Aqualad and Kid Flash that they investigate on their own. They would solve the case first and to prove to their mentors that they were ready for League membership. Robin’s computer skills were invaluable in breeching Project Cadmus and it was while rifling around in their database that he discovered Project-Kr. Against the better judgement of his friends Robin took them deeper into Cadmus where they discovered Superboy, a teenage clone of Superman illegally created by Project Cadmus.

The three sidekicks liberated Superboy and escaped with him to the surface. However, their way was blocked by Mark Desmond, Cadmus’s chief scientist, who had transformed himself into the Blockbuster to stop them escaping. The non-powered Robin was out of his depth physically, but it was his guidance that directed his superpowered friends to bring the roof down on Desmond. As Robin and co pulled themselves out of the rubble they found themselves face to face with the full Justice League and a very unamused Batman who told them “you will not be doing this again!”  They protested and Robin told him “Batman we’re ready to use what you taught us or why teach us at all?” (“Independence Day”, “Independence Day”).

Batman’s response was to set Robin, Aqualad, Kid Flash, Superboy, and Miss Martian up as a Justice League splinter group called based in the League’s old Cave headquarters. They were to be a covert group that would operate outside of the media spotlight which was usually focused on the full League. Robin joined them in civilian clothing, but was forbidden by Batman from revealing his secret identity (“Welcome to Happy Harbor”).

Robin as the most experienced sidekick and as the sidekick of the Justice League’s leader assumed that he was Young Justice’s leader. At the first sign of trouble Robin would usually vanish into the shadows to set-up a covert ambush or carry out some stealthy reconnaissance and assumed that the rest of Young Justice would do likewise. This frustrated his team-mates as they didn’t know where he was half the time and they were unaccustomed to the style of unspoken cooperation that Robin had developed with Batman.

Matters finally came to a head on their first proper mission, to investigate a Venom factory Santa Prisca, when Kid Flash and Robin got into a blazing row over his presumption of leadership. Aqualad told him that “a leader must be clear, explicit, he cannot vanish and expect others to play parts in an unknown plan.” Robin was mature enough to recognise that he was right and pointed out that Aqualad was the only logical choice to lead them. Aqualad accepted Robin’s judgement, but told him that “you were born to lead this team, maybe not now, but soon” and promised to relinquish that role to him when Robin was finally ready (“Drop-Zone”).

Robin is a natural gymnast, but often has to rely on stealth, speedy, and wits to compensate for his small stature. He has been trained by the Batman and is technically the most experienced member of Young Justice. The skills Batman taught him include computer hacking and he uses a wrist mounted portable computer with a holographic interface to crack into whatever systems – be it the Justice League’s own computer or Cadmus Lab’s mainframe – that he needs to.

Robin is never without his utility belt (Batman’s first lesson). Its contents include a grapple line with 26-story reach, explosive throwing discs, and conventional batarangs.