At least some content in this article is derived from information featured in Harry Potter: Hogwarts Mystery. Spoilers will be present within the article.
He was friends with Jacob from his first day at school until his dying day. The two were noted to be mischief makers by others, and frequently visited Zonko's Joke Shop. At some point, he and Jacob also broke their brooms. He was also friends with the school poltergeist, Peeves. Sometime during the 1970s and 1980s, he died of an unknown cause of death. After his death, Duncan returned as a ghost and stayed at Hogwarts, though he rarely showed himself to the other residents of the Castle.
- Harry Potter: Hogwarts Mystery (Appears as a ghost or a spirit)