So Barry Allen (pre-Flash) is now on Arrow. As of right now I don't know where his character is going, but I presume he lost his job in and he now knows Oliver's secret identity so maybe he'll join the team. I'm wondering if he'll eventually become The Flash on the show and become a recurring character to some extent or if The CW is levering this to start a spin-off with some crossover potential. I've always like The Flash as I enjoy his humor, rarely serious beta male style of superhero compared to your more typical serious, tough guy, alpha male superhero (Green Arrow, Batman, Superman...)
We'll see I guess.
(Use spoilers for un-aired verified future events on Arrow, not speculation or historical information about The Flash)