It was one of their "good" days.
They hadn't even hissed at Asgore when he came to visit. Papyrus was somewhat relieved and somewhat frazzled. They'd been running around the kitchen all day long. He wasn't sure they should be baking, but they seemed to know what they were doing, and more importantly, it seemed to make them happy; so he allowed it.
Although he made sure to check on them every five minutes.
He was about to get up from the couch to check on them again when they were suddenly right in front of him with their finished confection.
"Papyrus! papyrus! hehehe," they enthusiastically hailed him, proudly displaying the pie.
They were speaking coherently. Another sign that today was a good day. Papyrus hoped that they'd start having these more often. Maybe even make a full recovery?
"YES. YOU MADE A PIE. GOOD JOB!"
It was even a edible looking pie! The top crust seemed perfect, crispy and buttery.
"try some?" they offered.
Their eyes were twinkling in that familiar way... just like Sans' used to when he got excited. Papyrus sighed, but tried to hide his nostalgia from them. They didn't like it when he was sad.
"OF COURSE, BRUH- UM. OF COURSE I'LL TRY SOME!" He tried to shake away the twinge of grief and took the pie, carrying it to the table.
He was surprised as they pushed him forcibly into his chair and plopped a spoon right into his gloved hand. They expected him to eat it out of the dish? He tried to stand up but they pushed him back again.
"no. Hehehehe. try it! Try it!" They hovered over him expectantly.
"I WAS JUST GOING TO GET MYSELF A SLICE..."
"Try it! heh," they insisted.
"..."
Something was up. Papyrus narrowed his sockets at them suspiciously. They just snickered to themselves, shoulders shaking and eyes twinkling. Like Sans' used to. When he was about to tell a really awful pun or some other mischievous behavior...
"try it..." they whispered with a wide grin.
Papyrus sighed again, but finally gave in. He stuck the spoon into the pie.
PHBRBPHRBPHBRT!
The top crust flaked and cracked away at the invasion of the spoon, revealing... a whoopee cushion.
"AAAAAHAHAHAHAHAHAHAAHAH hAHAHAHAHAHAHAHAAHAHA!" they were hysterical.
Papyrus set the spoon next to the pie pan. He wanted to shout and scold them for the immature prank, but this was such a huge step. He just sat in conflicted silence while they rolled around on the ground giggling like idiots.
They finally calmed down enough to stand and regain some composure. They seemed to be wiping a tear from one of their eyes. They let out a final contented sigh as they made their way back into the kitchen, coming out with their real pie.
As they set it on the table, Papyrus couldn't hold himself back any longer. He grabbed them in the biggest hug he could manage. They seemed surprised at first but quickly wrapped their arms around him, returning the embrace.
"I'M FEELING SUCH A STRONG MIX OF PRIDE AND FRUSTRATION RIGHT NOW!" Papyrus exclaimed.
They held the hug for a bit longer before they finally broke apart. Papyrus looked down and found his battle body was covered in gross white goop.
"EEEEH... I THINK I WILL TAKE A SHOWER BEFORE WE EAT YOUR REAL PIE..."
"heh." they laughed softly.
As Papyrus dashed off to clean himself, he realized that this was the biggest his grin had been since... Since that day. He hadn't felt like this for so long. It was nice.
"NYEH HEH HEH HEH!"
After his shower, they all had some cinnamon apple pie. He even indulged them and told a few puns. Papyrus smiled and and was filled with hope.