I'm the King of Curry at Hogwarts

In the summer of 1991, Louis Jr., the young man from Old London, received his Hogwarts acceptance letter.
From that moment on, the students of Hogwarts were plunged into a lifelong nightmare.
Years later, when Hermione Granger, now Minister for Magic, was asked, "What do you think of the Prince of Hogwarts?" Granger shuddered as she recalled being swallowed by a mimic, being chased by the tree guards, and riding a roller coaster on Deathwing's back. In the end, a faint smile appeared on her face; those were their most carefree days.
"His Highness is the greatest alumnus of Hogwarts in history," she and Mr. Potter, the Chief Justice, replied in unison.
Note: The female lead is not Hermione, and the original couple will not be broken up.