A collection of Papyrus headcanons (not from any specific au, just from my brain and possibly my own au if I ever commit to it)
His eye sockets aren't as big as Sans', resulting in no eyelights and poor vision (the only evidence I have from off the top of my head is when he couldn't differentiate between Frisk and a rock). He has the power to manifest eyelights, but doing so for too long gives him a headache.
Papyrus has blasters, he just chooses not to use them. They're lethal, someone could get hurt!
(He's got autism strength and is aware of it, hence why he seems to "hold back" during a fight. He can get rough if not paying attention. Yes I'm projecting but I'm an autistic man who sees a lot of myself in him shush)
He DOESN'T hate dogs!!!!! He's terrified of them. A scary experience as a babybones scarred him for life.
(A pup got a hold of his tibia and dragged him around Snowdin. Not life threatening, but those kinds of things stick with a kid, y'know?
He is aware of the resets. He is aware of the alternate timelines. He just doesn't remember them, and he can't figure out why.
This causes major deja vu at least twice a week.
Undyne once told Papyrus "you're only as great as you think you are". Ever since, he's taken to calling himself The Great Papyrus so that everyone has a positive example to follow.
Papyrus would never think of anyone as "beneath" himself! Even his lazy brother Sans is just as great as The Great Papyrus!
He knows Flowey isn't just a silly talking flower! ...but he's not allowed to mention this to Sans. It's a best friend secret!
Papyrus doesn't sleep often—he thinks sleep is such a waste of time! It's not because he has horrifyingly strange dreams or anything, that would be absurdly specific!
(But it is definitely the second biggest reason. Imagine dreaming getting your head cut off, having all your bones snapped by long prickly vines, watching your brother be killed by a human child, watching yourself kill a human child. It's not the most fun to think about, is it?)
Hotland is dangerous. Papyrus hates Hotland.
Papyrus also hates Alphys' lab.
Papyrus loves the color red!!! Red is bold and strong, just like he is!!!!!! Orange is also pretty cool, but not as cool as red.
Papyrus knows Undyne doesn't particularly want him to join the Royal Guard. Sometimes, he's not quite sure he wants to either.
But if it makes him as cool as Undyne, and it helps Monsterkind reach the surface, it can't be too terrible! Right?
Papyrus doesn't like the feeling he gets when he sees himself in glasses (but super awesome sunglasses are okay!!!!)
He has a MySpace and posts regularly!