#40: The Color Blue
It isn’t until season 2 that we discover that Hopper had a wife, Diana, and a daughter Sara once upon a time. Sara, unfortunately, got really sick and passed away, and Hopper and Diane weren’t able to ever come back from it, so they got divorced and Hopper himself never recovered from the whole ordeal, until he met Eleven.
His daughter Sara used to wear a blue hair tie that was seen on Hopper’s wrist in seasons 1 and 2 until he gifts it to Eleven before the snow ball at the end of season 2. If you watch close enough, you can see that she is still wearing it in season 3. Hopper is even seen playing with it on her wrist before they go off and fight on their individual endeavors.