Washington DC, Feb. 20 -- A sweet birthday post, a throwback pic, and a few heartwarming words, sometimes that's all it takes to remind fans why the friendship between Millie Bobby Brown and Noah Schnapp is one of the most beloved off-screen bonds to come out of 'Stranger Things.'

Milllie turned 22 on Thursday, February 19, and her longtime best friend Noah made sure the day didn't go by without a public dose of affection for her Stranger Things co-star. Taking to his Instagram Story, Schnapp shared a black-and-white photo of the two sitting together in a car.

Along with the picture, the actor penned a deeply personal note that spoke volumes about their years-long friendship. Calling Millie his "longest friend," Noah wrote that he would...