Relating to the topic of height with the skelebros, I always had this scenario in my head that after Papyrus (maybe around 15-16ish years of age) finally finds peace with the fact that he will never grow taller, he grows around 2-3 ft in one night and doesn’t notice until Sans points it out to him.
Idk, I always thought it would be cute if they always had a height difference, even before Papyrus grew taller than him. Not to mention having Papyrus go through a terrifying growth spurt in one night would cause some amusing scenarios lol
Up through age 4, they're the same size.
Age 5, Sans grows a little taller.
Age 6, Sans is definitely outpacing Papyrus with 3 inches between them.
Age 10, Papyrus is finally 4 feet tall. The gap is 7 inches.
Age 16, Sans has reached his adult height. Papyrus has not grown at all, and his voice has not changed. But Papyrus is not disheartened! He's still a growing boy!
Age 17, everyone (except Papyrus) is sure that Papyrus is just going to be a pipsqueak for the rest of his life.
Age 18, Papyrus goes through all of puberty in a single night. Sans tucks him in as a squeaky lil boy and he wakes up A Man. He greets his brother in the morning with "SANS, I DECIDED TO GRADUATE PUBERTY" as if he planned for it to go this way. For all we know, he did. It's either the only time he's caught Sans so off-guard that he shouted and jumped out of his metaphorical skin, or Sans also treats this as just a perfectly normal Papyrus Thing: "proud of you, bro."