A fan asked the writing team for Stranger Things 4 if they could reveal any details for the upcoming season using Florence and the Machine songs. Well, they didn't ask so much as challenge. Which is brilliant. It's much harder to resist a challenge.
The team pointed to Florence's song "Cosmic Love" and fans are now inferring that this could mean the character Eleven turns evil. Especially because these were the specific lines pointed to:
And in the dark, I can hear your heartbeat I tried to find the sound/But then it stopped, and I was in the darkness, so darkness I became.