There are, of course, actors running around, but Aronofsky can't slow down long enough for anyone to create a decent character. Harry will have lots of company before it's all over. The goal is to make you understand how quickly the high can come and go, that these lost souls live only for that glorious moment. But it's a point that's been made so many times, and in so many other movies, you don't have to be told anymore. The repetitious skin-popping alternates with similar montages of people smoking pot, snorting cocaine and gulping uppers.
Nobody ever stops for a light snack.
It quickly becomes apparent that Aronofsky will be pounding away for the duration. The best approach is to just lean back, cover up, and let the director flail away until it's all over. That's not how movies are supposed to work, by the way. You're supposed to get lost in a film, not steel yourself to endure it. The subplot is actually the main plot filtered through an old woman's perspective.