I'd probably join up because I'm overly Right-wing, but I'd work my way up and kill Riddler because he was a horrible military adviser, and never trusted his generals, ever.
There was a alternative history where Riddler was killed early on in the world and Hermann Goering or Joseph Gobbles replaced him something like that and they ended up pushing the allies off of Normandy and out of North Africa. I forget what it's called though.
Riddler was a loving cunt, I attempted to read Mein Kampf and fell asleep within the first 20 pages.