We'll Meet Again/YMMV

• Complete Monster - There are several of these: Jose de San Martin, Napoleon Charles Bonaparte (the son of the one you know), Peter Cornelius, Jose Maria Torrijos etc, etc. Topped so far with Colonel Ricardo Goncalves.
• Historical Hero Upgrade / Historical Villain Upgrade - Different people have different destinies, as a principle of good Alternate History. Noted example is Jose de San Martin; Liberator in our timeline, horrific monster in the Alternate timeline, although far, far more powerful.
• Magnificent Bastard - -Edward Bismarck...very similar to the German we know and love in our timeline...only British, with the world at his fingertips, Maximilian Erhard when, unfazed by stalemate in France, decides to invade Britain for the heck of it and Sir Francis Tate.
• Moral Event Horizon - Louis XVII when he starts shooting protesters who he believes threaten the war effort; San Martin when he shoots the Pope;Erhard leaps over it when he orders the systematic starvation of Britain, Churchill when he orders prisoner massacres in the Third World War
• Nightmare Fuel - 'Case Study IV: Radiation Poisoning in the Public Domain'.
• This Is Your Premise on Drugs - An alt-American Civil War...earlier...with a much bigger 'Confederate States of America'...and at the same time absorbed in a war involving a separatist Ireland and raving Classicists wanting to take over the world...and they're all allied.