SPOILER WARNING: This article contains a spoiler for Wednesday's "Arrow" season finale.
In the midst of The CW's upfront presentation came significant casting news for one of its returning shows: John Barrowman will move to a series regular role for "Arrow" season three, as confirmed by The Hollywood Reporter.
Barrowman's character Malcolm Merlyn, based on DC Comics character Merlyn, was the primary antagonist of "Arrow" season one, and guest starred in a handful of second season episodes. This week's season finale set up a new role for the character: As mentor for Thea (Willa Holland), his biological daughter and Oliver's (Stephen Amell) sister.
Amell broke the casting news Thursday morning via Twitter:
What could go wrong?!?! pic.twitter.com/VgFQdQhKNq— Stephen Amell (@amellywood) May 15, 2014
"Arrow" returns with new episodes this fall on The CW, Wednesdays at 8 p.m.