Anyways, every day I become more and more convinced Mike has a stack of letters written to Will signed "Love, Mike" that will make an appearance in S5.
There's too much evidence:
Mike supposedly only writing to El (why not Will? Unless- *gunshot*)
Letters in general being brought up a lot throughout S4 ("El has a book of letters from you," El pulling out Mike's letters and throwing them at him, "I have gone to become a superhero. From, El," Mike throwing El's letter in the trash)
Letter to Willy being the title of [tender, emotional music]
Mike being the writer of the group, yet he can't write Will a letter (an interesting parallel because Will, the artist, used a painting to convey his feelings for Mike... so wouldn't Mike use a letter to convey his feelings for Will?) (inspired by @frodohaven 's post)
Mike's pocket over his heart shaped like a sideways envelope (also an arrow)... Mike being Will's heart... that jacket being made specifically for Mike by the costume designer
Mike hardly spoke to Will since S3, yet he had one of his drawings hanging up over his bed so he was still thinking about him a lot... what better way as a writer than to write down his thoughts?
The obvious parallel that would make Mike's feelings clear to the audience when his letters to Will are signed "Love, Mike" since S4 made a big point to reinforce (1) Mike's difficulty with telling El he loves her, and (2) "From, Mike"
The possibility that even if Mike confessed to Will, he might not believe him at first, until Mike pulls out the stack of letters and says, "see for yourself"
Or the possibility for a superiorly comedic scene if the Byers stay with the Wheelers immediately post-S4 of someone finding Mike's letters and dropping non-subtle hints about his feelings (to his embarrassment and Will's confusion)
