My personal pet peeve: ignoring the known personality of a given person in order to come up with a scenario the author has come up with. It happens most frequently in fanfiction, but here is a great example. Katherine of Aragon believed herself to be the lawful Queen (and she was crowned right alongside Henry) of England. She comes from warrior parents who were raising their children on the battlefield (so to speak). She ain't running. Period.
Now, Mary, OTOH, might be persuaded to bolt. But in doing so, she may forfeit the crown. Running and then coming back works for Henry Tudor (H7), but she's not built for battle (always ill) and the throne will pass with some small bumps (smoothed over by Parliament, after years of Edward VI, stating she 'admitted' the validity of Henry VIII's conscience when she fled the country. But......Charles V, HRE, is going to ensure she weds someone he can back for a fight. Mary might become Queen of England after wedding the HRE (they had been betrothed before) after his wife's death - just to give him a reason to enforce her claim. After all, both daughters of H8 are bastards. She would be in England, reigning, and he's in Europe, reigning (or perhaps hands over lands to Philip earlier to remain in England and "advise" his wife - he's the only person in that era who can afford to go "I don't need to be a reigning King" and accept the title of King Consort, all the while being the power behind the throne. And he's had the experience (and hopefully the wisdom) to give good, pro-English advice. (Which will surprise the council - he might even be more Elizabeth and be tolerant of people's personal beliefs.)