After her brother passed away in the Season 3 finale, her character on the programme similarly went through periods of depression and rage.
Sadie said, "It really helped me because I’d never done a project like The Whale or worked with someone like Darren. Working on that gave me this level of confidence in front of the camera that I did not have before."
She added, "So going back to Stranger Things after that, I felt really different and I think everyone could tell the difference, too. There was a shift. That comes with stepping out of the child actor role and into, I don’t know, your adulthood, where you stop seeing yourself as this little puppet that stands on their mark and takes direction. "