So you need to relate these three to various WWII era political systems?

I think that the most obvious one is Ralph.  Ralph represents democracies like those that the US and Great Britain had.  He wants to act in a civilized way that is fair to everyone and is based on consensus.

I would say that Jack would be a dictatorship of sorts -- either Japan or Italy.  He wants to rule by himself; he wants to be the strongman.   But I would not put him as Hitler, even though he does want to be a dictator.

The reason I say this is that Roger is more of a Hitler.  He is totally brutal and seems to enjoy violence and hurting people.  He seems more like he is out of his mind, which is really more characteristic of Hitler than of Mussolini or, especially, the Japanese leaders.