I'll leave Fritz' reaction (and Heinrich's!) to Mildred.
Fritz being the power behind the throne of the Emperor is a serious obstacle, but MT knows her son. He's stubborn, he's argumentative, he'll insist on imposing his own ideas on his olders and betters, she just knows this will happen. Also, he might be star struck by Fritz know and thus prone to do what Fritz wants for a while, but you know, the last person in a mutual admiration society with Fritz was Voltaire, and close contact cured that one as the whole of Europe knows. She intends to live and rule for more years to come, so her gamble is: physical proximity to Fritz will reduce Joseph's crush to manageable size.
As for the succession, well, she has already some grandkids of both genders. At least one can be married to one of Fritz' nieces or nephews. But it must be a Catholic.
Re: Crackfic
Fritz being the power behind the throne of the Emperor is a serious obstacle, but MT knows her son. He's stubborn, he's argumentative, he'll insist on imposing his own ideas on his olders and betters, she just knows this will happen. Also, he might be star struck by Fritz know and thus prone to do what Fritz wants for a while, but you know, the last person in a mutual admiration society with Fritz was Voltaire, and close contact cured that one as the whole of Europe knows. She intends to live and rule for more years to come, so her gamble is: physical proximity to Fritz will reduce Joseph's crush to manageable size.
As for the succession, well, she has already some grandkids of both genders. At least one can be married to one of Fritz' nieces or nephews. But it must be a Catholic.