Yann began attending Hogwarts School of Witchcraft and Wizardry on 1 September 2017 and was sorted into Gryffindor. During the sorting ceremony, he remarked that Albus Potter had hair just like his father, Harry Potter. He sardonically retracted this comment when Albus was placed in Slytherin a short time later.
Yann was able to raise his broomstick on the first attempt during the first years' initial flying lesson with Madam Hooch. The only other student in the class who accomplished this feat was Rose Granger-Weasley.
Upon returning to 2020 after altering the past, Albus Potter and Scorpius Malfoy found themselves in an alternate reality, in which Albus was a Gryffindor and Hermione Granger taught Defence Against the Dark Arts. During a lesson, Albus questioned her about the changed circumstances, prompting her to deduct points from Gryffindor. Albus persisted, however, prompting Yann to threateningly insinuate that he would do something to Albus if he didn't stop.
After finding himself in another alternate reality, in which Lord Voldemort won and Albus was never born, Scorpius was greeted by Yann and Karl Jenkins in the Hogwarts grounds. Yann asked Scorpius if he was still on for an event the following night and Karl enthused they were both ready to "spill some proper Mudblood guts."
Behind the scenes
- In the original West End production of Harry Potter and the Cursed Child, Yann is played by James Le Lacheur.