The Flash spoilers follow.
The Flash showrunner Eric Wallace has opened up about the decision to conclude a long-running Arrow storyline in a recent episode.
A few weeks ago, fans were reintroduced to John Diggle (David Ramsey) as he approached Eobard Thawne (Tom Cavanagh) about opening his cube.
When he manages to open the box, however, Diggle realises that he wants none of what it has to offer, throwing it away before it disappears into the void, provoking Thawne's anger.
"I am someone special," Diggle hits back. "I now realise the cube was trying to make me someone else… something else. But there is no power in the universe more powerful than the love I have for my family."
Opening up about the decision to wrap the storyline up now, Wallace admitted that the season's finale was written before The Flash was renewed for season 9, so they felt obliged to tie up Diggle's arc now amid the uncertainty.
"We were thinking, 'Oh my goodness, we have to do this because maybe no one will get a chance to!'" he told TVLine.
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"I talked to David [Ramsey] myself, and told him, 'I'd like to give this some closure', and he was all in favour of it. And when I told him what we had planned, he thought it sounded fantastic."
Wallace also explained that the conclusion "served a larger purpose" by teasing the 'Blackest Night' storyline from the original comics.
Speaking further about the possibility of jumping into that storyline amid uncertainty over whether season 9 will be the last, he said: "I'm a comic book nerd and I wanted to plant some 'Blackest Night' seeds, and that Diggle moment helped me do that.
"But I don't know if we'll ever get to it."
The Flash airs on The CW in the US. Sky Showcase and NOW air the show in the UK.