Spoiler warning if you haven’t seen it.
The concept of the movie is that you take this ‘substance’, a second younger version of you will grow out of your body and now you’ll be young again.
However, there is a catch.Your original body which is older is still needed, as your younger body will start to suffer and die after a week.
The idea is that the younger body needs to have some stabilizer fluid that is otten from spinal fluid or brain stem fluid or something…that only can be produced in the older original body.
So, after a week, you have to switch back to have your mind and consciousness in the older original body. If you don’t, the older body will start to heavily age, and it’ll also eventually stop producing the spine juice that will keep the younger body ticking.
The movie makes a big deal that both Demi Moore, who plays the older character Elizabeth Sparkle and Margeret Qualley, who plays the younger version, Sue, are ‘one’. They are the same person, even though there are two bodies that the mind is shared between. But like any Jekyll and Hyde inspired story, the two sides of the personality begin to hate one another.
When she’s older, the older one, Elizabeth hates that when she’s in the younger body of Sue, as Sue gets to have all the fun, whilst when she has to be old, Elizabeth has to do all the house work and effectively be a recluse.
The younger body, Sue then resents having to switch back to Elizabeth who gets to chill all the time whilst Sue has to go to work every day as a fitness model and celebrity.
No matter how much the mysterious suppliers of ‘the substance’ emphasise that Elizabeth and Sue are in fact one and the same person, the two sides of the personality see the other side as a separate entity who they don’t like.
However, as you’ll know if you’ve seen the film, the two sides of the personality are actually two separate entities.
Or are they?
Later in the film, certain circumstances arise so that both sue and Elizabeth are conscious at once, and fight with each other to the death.
But how can that be if there is only one mind between them?
If the rules of using the Substance were followed as the instructions told them to,
then effectively Sue and Elizabeth are indeed one.
Sue grew out of Elizabeth, so we have to assume that Sue is just meant to be a younger version of Elizabeth.
Now, obviously both Sue who is played by Margeret Qualley and Elizabeth who is played by Demi Moore are different actors and therefore don’t look like they are the same person.
We know what Demi Moore looked like when she was Qualley’s age and they are clearly not the same person.
