Stranger Things finale may have left a huge clue on the basement bookshelf

After almost a decade, Stranger Things has come to an end — and even though some fans aren't happy with how things left off, the finale still has plenty of people talking.

SEE ALSO: 'Stranger Things' fans are furious about the finale. Here's why.

One topic that's dominated social media is the ultimate fate of Eleven (Millie Bobby Brown). Towards the end of the finale the series protagonist appears to sacrifice herself by staying...