Greg responds...

I feel like I've answered this before, but...

I read a ton of comics, starting with the big black and white Showcase Teen Titans reprint volumes and all the Young Justice comics that I could get my hands on, plus a few other random things, including most of my own collection of New Teen Titans, Flash, Green Lantern, DC Comics Presents, Captain Atom, etc. I also watched a bunch of episodes of Justice League, Justice League Unlimited and Teen Titans. (Although this was mostly done to avoid copying what they had done.) I also read through (or at least skimmed) pretty much the entire DC Encyclopedia. Occasionally, I'd do a quick check of something on Wikipedia and/or ComicVine or my own old issues of Who's Who. And when I needed to go deep - John Wells was there to help out.

Plus, keep in mind that I'm a huge geek that's been in this game professionally since 1983 and reading comics since, 1969ish... So I knew a lot of stuff already. Plus there's Brandon and Phil and a ton of other geeks that worked on the show.