The way in which Duncan Scott prevents Charles's insanity in "The Desjardins" from becoming a bad joke is by employing the following techniques.

• by adding Gothic elements to the story- the mysterious nature of the Desjardins insanity problems in the story make Charles an enigmatic character rather than a funny one. He does use comedy when explaining Charles's behavior, but the parameters within which this is explained curb the tendency to make a joke and, instead, invite the reader to explore further what could be the consequences of Charles's behavior.
• by adding consequences to Charles's actions - it is clear that the insanity problem within the Desjardins is a perpetual worry to the family. By creating a concern in Adele and Phillipe, Scott demonstrates how Charles's issues do carry a weigh that could develop into a very sad ending.

Adele and Phillipe demonstrate a genuine concern for their brother; they even carry on the brother's fantasies and refer to him as "Sire", when needed. This may very well be humorous. However, it is in the subtle details that Scott makes the strongest points: when we see the tender reactions of the siblings towards an ailing brother, his illness, funny as it may make him, is no longer funny. Instead, it creates feelings of sympathy and tenderness in the reader

Charles dropped on his knees beside the table against which Philippe was leaning. He hid his face in his arms Philippe reaching across thrust his fingers into his brother's brown hair. The warm grasp came as an answer to all Charles's unasked questions he knew that whatever might happen his brother would guard him.

Therefore, Duncan Scott mixes emotional sympathy, tenderness, Gothic elements, and enigma to make Charles an interesting, and not just a mirth-tapping character.