What if—
Steve Harrington has an audio processing disorder and that's why he was staring at Eddie's lips in the Upside Down? Like, he certainly doesn't mind staring, because they're attractive lips. But also, it wasn't initially due to infatuation or flirting.
And then, when everything is over, him and Eddie hang out a lot. And Eddie notices that Steve still stares at his lips—like a good 99% of the time. So he just leans in and kisses Steve.
And Steve like blue screens, essentially. Like that's his moment of realization? It's not like he wasn't aware of his feelings for Eddie, but he didn't realize how badly he wanted them to kiss. But now that it's happened, he has even more of a reason to keep staring at Eddie's lips. (Even though it definitely doesn't help that he stops listening and processing whatever Eddie's saying, because he just wants to kiss so bad. So Steve has to kiss Eddie every once in a while to shut him up and then ask for him to start over. And Eddie isn't bothered by this, just rolls his eyes and fakes annoyance.)
(This is brought to you by the fact that I stare at everybody's lips and yeah, sometimes I want a kiss. But also, what the fuck are you saying? I have to know.)
Edit: I reblogged already, but there's a little drabble now, if you're interested! The link can be found here!