Due to the strengths and reaches of Papyrus' emotions, he feels much more strongly about things than others. This extra emotional weight he carries causes mood swings and a quick mental trigger. He can be overjoyed one second, heartbroken the next, and breathing fire the next... literally.

Fuku taught him how to use fire magic, and he had such a natural gift for it that it often sparks when he doesn't intend it to. This often scares the people around him, except for Fuku. Luckily, he never lights anything on fire, but it looks scary as hell and sends him coughing up smoke for about ten minutes after he's calmed down. Sans is the most frequent victim of the flaming outbursts, with his chronic laziness and constant bad puns always irritating Papyrus right below his breaking point, but he has grown used to it over time and helps to calm his brother down.

I like making cinnamon rolls edgy