I have a theory that this song is about the murders of Kristen French and Lesley Mahoffey. Which took place in st Catherines around the same time or I mean shortly before. Those murders changed the city from safe suburban town to a place people were scared to live in. Haunted city by their ghost

While writing his album Je Reviens À Toi, Marc was unfortunately surrounded by the deaths of both his parents, to whom he referred earlier in his songs "Reviens Mon Amour" (his father) and "Ballade Pour Michelle" (his mother), his first wife Denise Paschall, and some of his friends who died of AIDS as well. So with all these losses, he felt like he was alone, definitely.

Marc wrote it in reaction to a friend who lost his son in an accident. In fact, he put himself in his friend's place : bidding farewell to his deceased child and gireving, dealing with this unbearable pain.

A French teacher was brutally murdered by a Russian terrorist in Conflans-Sainte-Honorine more than a year ago. At the opening of the teacher's national funeral, it was one of his favourite songs.\n\nRemembering the French geography teacher who got decapitated on October 16, 2020. Mr. Samuel Paty. As the next week started, tears took over, between sadness and indignation. 5 days later, I felt a premonition in the morning : because of that and not my accentuated shyness, I refused to sing in front of my parents, and both respected my decision that I had the right not to sing. That evening, I haven't watched his national funeral on television but I heard how it was on the 5am news, the following day. And a big smile on my face, a sign that my premonition worked : there was this song from 30 years ago at the beginning, a wonderful, universal brotherhood anthem, one of the teacher's favourites, and it means a lot to me because this band reminds me of my youth.

Let’s respect what the man himself says. https://faroutmagazine.co.uk/lou-reed-perfect-day-heroin-real-song-meaning/