When Barry Allen went back in time to save his mother in The Flash season 3 it lead to a new timeline called Flashpoint. Although Barry quickly realised his folly and returned back to the old timeline, but there remained certain side effects of that in Arrow season 5.
In episode 2 of The Flash season 3, Barry realised that John Diggle's baby daughter Sara has been replaced with a son named John. Previously, executive producer Marc Guggenheim in an interview addressed Diggle and Lyla's daughter change. He said, "I always say that, on Arrow, there is no secret that doesn't eventually get discovered."
David Ramsey, who plays Diggle in Arrow season 5 spoke to TVLine about his character's reaction to the Flashpoint twist. Ramsey said, "I can tell you, it is important that he finds out. Secrets don't say secrets for long on this show — or in any of these Berlanti universes."
The actor also has a good idea of how John will react to his gender twist. "Diggle can't miss something he's never had. So it's less what we know or think his reaction might be, because we have the benefit of knowing he had a daughter I think his reaction is going to be a lot more compassionate than you think toward Barry, who has this extraordinary power and just kind of recklessly used it."
Although Diggle may be okay with the changes, some Arrow fans were however not happy with the altered offspring. Ramsey revealed, "They were really pissed off! And I was like, 'Really?' I mean, Sara was cute, but I like little John Jr. He is cool, a little ham."
The Flash season 3 airs every Tuesdays at 8pm EST on The CW Network and Arrow season 5 airs every Wednesday at 8pm EST on same network.