Bathtime with the blasters -- Gallifreya
[AN: There are so many headcannons wandering around Tumblr about the Gaster Blasters (Spoilers: They are only seen in the No Mercy run when you fight Sans) but the core of this one is that Papyrus can summon Blasters, but they're cat skulls]
There were two words that Papyrus' Blasters hated the most.
And, as summonable creatures, there was little they could do about it. Not that they ever stopped trying. The spacious backyard that both skele-bros enjoyed was full of cries and orders.
"Bitty! Come on, now, it isn't that bad..."
"It's going to take longer if you fight!"
"Claude! No flying! Bad kitty!"
Sans, meanwhile, calmly hosed off his Blaster. Predictably named Boom because it was short and easy to remember. "Let 'em wash themselves," he said for what felt like the millionth time. "They're okay."
"Sans! They don't have tongues. And they don't have paws. It's my duty as a responsible owner to make certain they're clean."
Three of the sorriest-looking cat skulls sat in fluffy towels and whined piteously. Papyrus did his best imitation purr as he gently wiped them dry. "There we go," he cooed. "There, there..."
Boom, now clean and dry, bounded across the yard to leap into the kiddie pool and splash water all over the already-soaking Papyrus, and the nearly-dry kitty Blasters.
All three of them screeched and hissed, scattering in three different directions.
Up on the second balcony, far above the spray line, Frisk giggled.
"More popcorn, my child?" offered Mama Toriel.
Frisk nodded, grinning. Blaster Bath Day was the best.