User blog comment:Eobard95/Problems with Prometheus/@comment-27673963-20170615083043/@comment-29493700-20170615162023

I like this theory. Team Arrow, Team Flash, the Legends, and Supergirl all spent at least a week together during the crossover event. It'd be safe to say that Adrian kept tabs on what was happening. No coincidence that a week later after the crossover, Black Siren showed up at the Arrowcave.