SPOILER WARNING: This article contains major spoilers for "Purgatory," the latest episode of Arrow Season 8.
In "Purgatory," the latest episode of Arrow, a series of events altered the future as Mia Smoak, William Clayton-Queen and Connor Hawke know it.
Perhaps the most violent example of this happened to Roy Harper, aka Arsenal. While Oliver and Laurel were personally transported to Lian Yu by the Monitor, Roy had to travel via plane with Dinah Drake and Rene Ramirez. As they approached the island, they were attacked; a missile shot the plane down, resulting in an explosive crash. Roy was thrown from the plane and pinned by debris. Diggle and Connor were forced to amputate his arm to free him, irrevocably changing his life.
When William and Mia encountered Roy for the first time in 2040, he was intact, with both arms fully functional and accounted for. This means the path Roy was on has changed, as he can no longer fire a bow without a prosthetic, and the fallout from this is sure to be massive. There is simply no way for the events of Season 7's flash-forwards to unfold as William remembers it.
Further, Lyla's transformation into Harbinger has altered another key piece of Connor's past. As Lyla, Diggle and Connor scourged the jungle for plane crash survivors, he revealed something important about Lyla and Diggle's future: "I was beyond proud to be the son of the two super-spies that co-founded Knightwatch."
However, that changed when Lyla became Harbinger. When she appeared to Oliver and Mia wearing her new costume, Oliver called out her name. "Not anymore," she informed him. "I'm now a harbinger of things to come." This suggests Lyla -- the wife of John Diggle and mother to JJ and Connor -- has ceased to exist. In turn, Lyla Michaels is no longer around to co-found Knightwatch. Perhaps the organization will still be formed, but it may now be without Lyla's help.
Additionally, Oliver asked Diggle for a favor on behalf of his children. "When this is over, track down Felicity and just tell her that I don't want Mia and William kept separated," he said. "I think that they deserve to grow up with each other."
"I'll tell her," Diggle replied. If he carries through on this promise, he will forever change the route of the Queen children. As revealed last season, William was raised by his maternal grandparents, while Felicity raised Mia in secret. Should Felicity listen to Diggle, she would alter their childhoods in a fundamental way, changing their dynamic as it has appeared on the series so far.
Airing Tuesdays at 9 p.m. ET/PT on The CW, Arrow's final season stars Stephen Amell as Oliver Queen, David Ramsey as John Diggle, Rick Gonzalez as Wild Dog, Juliana Harkavy as Black Canary, Katie Cassidy as Black Siren, Katherine McNamara as Mia Smoak, Joseph David-Jones as Connor Hawke and Ben Lewis as William Clayton-Queen.