Harry, un ami qui vous veut du bien / With a Friend Like Harry... (2000)

On a hot day in a highway gas station men's room, a man Michel doesn't recognize says they went to school together. He's Harry. He suggests they have a drink, so he and his girlfriend follow Michel and his family to their summer place. Michel is amazed when Harry quotes from memory a poem Michel wrote in school. Harry thinks Michel is a great writer, and he's distressed that Michel hasn't written in years. Harry stays awhile (since his father's death, he's a man of leisure) and sets out to eliminate distractions that might keep Michel from writing. First he buys Michel a car (with air conditioning) and then suspicious things happen. Michel picks up a pen, Harry is gratified, but he's not finished being Michel's self-appointed patron.
Imdb