When You Least Expect it, Expect it…
To avoid spoilers, I dare not say much about Renny, beyond the fact that casting a truly effective foil for Gideon was tough. I wanted someone who could match Gideon's level of snark, who had a twisty way of thinking, who was, in many ways, a mirror image of Gideon.
This was not an easy task, and Renny's character, and his actions, underwent a significant number of rewrites until I fixed on the actor whose voice could best stand up to Gideon's mercurial moods and quicksilver flashes of genius-slash-insanity.
Also, loved his cameo in the Arrowverse Crisis on Infinite Earths.