What if the Legacy line was ambitious?
Joseph Parsons gets way more involved in the American Revolution, and ends up becoming sort of an elite strike commander for Washington. When Washington becomes President, he apoints Joseph Parsons as the head of Military Intelligence. Joseph commands the Bureau for decades.
During the War of 1812, Paul Parsons is awarded a medal of valor for commanding the American defense of Washington DC, and drawing a truly impressive amount of British Blood there. He ends up commanding the American invasion of Canada. Though he doesn't conquer all of Canada, he does seize Ottawa, and convince Quebec to rebel agaainst the British. Quebec then joins the US as a State in 1822. These successes propel Paul Parsons all the way to the White House in 1824.
Paul Parsons the First has been elected to his third term, when he makes a controversial decision. He tries to abolish slavery. This immediately kicks off a fracture and almost civil war. However, Paul crushes the dissidents with the assistance of his son Paul the Second. Afterwards he argues that all now freed African slaves should be full citizens. With all the things he has done, h has enough pull to basically rewrite the executive powers. He basically makes it so the President appoints their successor. After a few more years of rule, he appoints his son as the new President.
This works in large part because most of the day to day running of the country is done by state and congressional individuals, who are still elected. Additional, most of the Parsons who aren't president at any given time are high ranking military officers.
During the Mexican American war, the rumors of the Parsons being supernaturally blessed is proven true when Paul the third smashes down a city wall wih his bare hands. This, along with slavery being a dead institution leads to several Mexican provinces being integrated as States. Also, no Andrew Jackson as president, so no trail of tears and a lot more Indians in the Eastern United States.
Later, during Paul the third's presidency, Paul the Fourth leads a campiagn to conquer the rest of Canada. This leads to a largely united North America Under Parsons rule.
Things go broadly pretty good until World War 1 kicks off and Paul Parsons the sixth leads a American volunteers to join the war on the side of the Germans in 1916. His flight and power is so impressive that it leads to a few other super humans showing up and being recruited by the US government. Notably, Paul the sixth recruits a scientist called Fyodor Ramonant and helps him to get to safet in America.
America's dominance in Super heroes leads to a sandoffish relaionship with the great powers of Europe due to these unique advantages. Over time, the US widens the technological gap between them and the European powers thanks to Fyodor Ramonant, Henry Goodman, and, eventually, Meredith Stinson and Ivan Ramonant
This starts to lead to an upperclass of Superhumans and genius inventors. This leads to the modern day, where President Paul Parsons the 8th leads an United States that spans North America. At his hands he has agents like Ivan Ramonant, Dawn Cohen, and Meredith Stinson.
However, they are opposed by a sort of rag-tag opponents, sort of downtrodden, not really super humans, including Ambuscade, Wraith, and Sofia DeLeon.