So, this was something I discovered by accident.
It appears that in 1814, Charlotte of Wales, daughter of the future George IV, was quite interested in marrying Frederick, Prince of Prussia, son of Prince Louis Charles of Prussia and his wife Frederica of Mecklenburg-Strelitz (who would later marry Ernest Augustus I of Hanover), however, the marriage plans were interrupted when Frederick suddenly married Luise of Anhalt-Bernburg
My query is, what would've changed had instead of becoming engaged to Alexius, Frederick and Charlotte had indeed married. Otl, Charlotte died in childbirth, and Fred had two sons with his with. Let's assume that Charlotte successfully delivers a reasonably healthy baby boy, in 1815, that prevents some of the later succession issues I imagine.
What sort of role could Frederick have as the second in line's husband? He was quite the military man otl, would he look to pursue a similar career here?
What would their marriage do for relations between Britain and Prussia?
Edited