Tonight was a game changing episode of "Arrow" for David Ramsey's character John Diggle. While giving his brother Andy (Eugene Byrd) chance after chance at redemption, Diggle had to make a shocking decision that will change the course of his character forever.

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Throughout the episode Andy kept getting the upper hand on Diggle. First Andy kidnapped Diggle and planted a tracking device on him. Once Andy discovered where Diggle, Lyla (Audrey Marie Anderson,) and Sara were hiding, he and Darhk (Neal McDonough) attacked them. Both times Diggle had the opportunity to kill his brother for betraying him, but he continued to exercise mercy.

In the final showdown between Diggle and his brother, Andy told Diggle to kill him. Andy had been taunting Diggle all day with the memories of Laurel and his betrayal. It wasn't until Andy crossed the line, by saying that he would always come for Lyla and Sara, that Diggle knew he had to put Andy down. In their final moments together Diggle shot and killed Andy, which ended H.I.V.E.'s reign of terror against Diggle's family.

It was an emotional and surprising move for Diggle to make, considering he had been after Andy's supposed killer, Floyd Lawton, for years. Diggle had also been a strong voice of reason in Oliver's life, urging him not to take life, to let the criminals of Star City face justice in a court of law. Now Diggle will have to live with consequences of not just taking the life of one of Darhk's thugs, but his own brother.

Tonight's episode also shed some light on Darhk's ultimate Genesis plans, as Lyla realized the only reason Andy tracked Diggle was to get to her. As the newly appointed director of A.R.G.U.S., Lyla was carrying a program called Rubicon. Darhk cut it out of her arm and plans to use it to level the world in a nuclear war.

Check out the full breakdown of tonight's episode in CBR's "Arrow" recap here.

"Arrow" airs Wednesdays on The CW at 8 p.m.