Maybe Will doesn’t like milkshakes. Actually, I think this might be exactly why they used the milkshakes from Melvald’s in coming out scene. Will didn’t have one in Season 4 when others had a milkshake, which makes me wonder if it was intentional.
Maybe he's trying to give Mike some kind of cryptic clue. Or maybe his memories are starting to overlap with Henry's.
Note: I just want to mention this too. If Will wanted a milkshake, he knows how to buy one. He doesn't need someone else to get it for him, he's not a baby. One of Will's biggest frustrations is that people, other than Mike, often treat him like he's younger or more fragile than he really is. That kind of overprotectiveness can feel suffocating, and I don't think he likes being treated like a child. Also, why are you looking at him like that Mike? Will is pretty when he is mad! (Mike in his mind)












