While talking to IGN about his role in the upcoming live-action Titans show on the DC Universe subscription service, Dick Grayson/Robin actor Brenton Thwaites explained that it was Batman’s murderous methods that drove Robin away, which is why the show finds Robin fighting crime solo in Detroit instead of Gotham.
“Batman is a killer and Robin wants to get away from that,” Thwaites said. “The idea is that he doesn’t want to become a killer himself. And although these guys that he’s fighting are bad and they deserve, you know, they deserve what he’s dishing out, it seems, he believes that when you kill someone you crossed the line and you become almost as bad as them, so it’s pretty clear in the series that he was with Batman, Batman crossed the line and he was teaching me to do the same thing, and he’s trying to break away from that.”
Source: IGN.com Robin Actor Says Batman Is a Killer in DC's Titans