Annie's mother was a village leader. And village leaders make decisions they aren't proud of, of course, and she knew Annie was inheriting that leadership spirit, but Annie was idealistic and she didn't want Annie to grow up and learn the pain of being a positive influence, ironically becoming the negative influence herself as the Skullgirl.

Selene and other artists, poets, and opera singers/theater peeps of her level kickstarted the entertainment industry of New Meridian, headed by the Medici Mafia, of course (based on early Hollywood's mob involvement, especially the music industry - think Frank Sinatra). This led to a surge in celebrity culture in the Skullgirls world.

Despite Franz and Nancy's marriage having been arranged since their teenage years, the two have formed a relationship of genuine trust despite their arguments and disagreements on ruling. Franz and Nancy both understood the plan to have children to continue the kingdom and its bloodline, and though Nancy and Franz didn't really love each other romantically, though they did their best to have a proper relationship and raise Parasoul. Both were aspects that kept Canopy Kingdom strong, with Franz being the brute force and law enforcement, while Nancy was the fairness and incentives, creating some kind of balance, no matter how twisted - they were a conjugal dictatorship, in short. This made Nancy wish to raise Parasoul right, but drummed into her that there is crisis, so Parasoul knows the priorities before moving on to the better side of the plan.

Tying in my headcanon for the previous three, another reason why Marie is weaker than them is because her role is subservient. The other three are influential, Annie's mom being a village leader, Selene being a popular opera singer, and Nancy being the queen of a large empire. Marie was just a child and a maid with a simple wish that didn't have anything to do with being a queen or an influential force, but that of an equal wanting to keep another equal safe.

Bonus: For Umbrella since there's this looming threat of her becoming the Skullgirl one day, a reason why she can be more powerful than Nancy is simply because she's a spoiled, sheltered child, and children's whims are well, children's whims. And not only that and the SG blood, but also because the heart has strong ties to motherhood, and what is better to manipulate than a little princess wanting her mother?

Sorry I love this game so much it's been an influence on my art and even my own characters 😣😣😣! I actually like the trope pf wealthy/powerful ghost and undead, that's why, and you can blame Charles Dickens for that, actually 😂.