Suspense version: A middle school student in the 21st century traveled to the HP world. As a fan of Hamburg, where should she go?
Entertainment version: Surprise! A Ravenclaw student actually did this to a Hufflepuff senior
Online version: 108 ways to seduce your seniors wholeheartedly
It's probably like a time traveler who comes to the world of Harry Potter and becomes Harry Potter's senior. He just wants to learn and befriend Senior Cedric, and occasionally secretly helps Audio-Technica complete the main mission. It won't be too Mary Sue, and the characters will try not to be OOC.
Purpose: Relaxing entertainment, fulfilling the dream of going to Hogwarts, dedicated to you who didn't wait for the owl when you were 11 years old