if there is one things that I completely adore about byeler is their height difference so here are some headcanons of tol mike and smol will: 

• mike likes to tease will about his height most of the time; he puts his arm on will’s head and makes do as if he’s resting on him, he sometimes bumps into will on purpose only to exclaim “oh will, I’m so sorry, I didn’t see you there” or at times when they’re standing next to each other mike suddenly gasps and goes “where’s will?” and the others just look at him funny and point at will by his side so mike turns to him and says “ah sorry, you weren’t in my field of vision”.
  
• at first will finds all the teasing amusing, and he just goes along with mike, but over time he gets frustrated so whenever mike has a “i’m too tall” accident, he makes sure to laugh the loudest at mike’s misfortune like that one time mike bumped his head straight on a cabinet door because he underestimated his height and will laughed for half an hour straight .
• will also takes his revenge on mike’s teasing by making him do everything that will can’t because of his height. will wants something that’s too high? mike goes and gets it. the bulb isn’t working? mike goes and fixes it. 
• it gets to a point where it’s not even about height anymore, will just makes mike do things he’s too lazy to do. mike likes to complain but he does them anyway because he can’t say no to will. 
• mike loves to kiss will’s forehead every time he can, not only because will is at the perfect height for mike to do it but also because why the heck not? so whenever he’s close enough to do it? he goes in for it. will is embarrassed at first, his cheeks reddening every single time without fail,  but as time goes on and mike still doesn’t stop, will becomes used to it and starts taking comfort in the affectionate gesture. 
• when they cuddle mike likes to do it facing each other, he circles his arms around will’s waist and brings him close, puts his head on will’s chest so he can hear the soft thump thump thump of will’s heart and reassure himself that will is there with him. will for his part hugs mike even closer to him, lays his head on mike’s and starts to hum under his breath whatever song comes to his mind, lulling them both to a peaceful sleep.
• sometimes when will can’t seem to find his asleep, he will play with mike’s soft curls and twist them between his fingers until he feels exhausted enough that he can’t keep his eyes open. 

and so many more scenarios ;u; my mind is full of them.