Bed Time
A few months after the Undertale plot :
Sniff, sniff...
Through his dream, where Frisk was riding a wild meatball as a cowboy and Papyrus was throwing a lasso of spaghetti to bring it back to the pastures, the child thought he heard a strange, muffled noise.
Faint, then it became more distinct and distracted him from the dream which faded.
What is this ? The child opened eyes and rubbed his tired eyelids; he saw nothing, obviously. Earlier, Toriel had tucked Asriel and Frisk together, before putting them to bed and turning off the light. Hanging from the ceiling, the glowing star-shaped stickers were not enough to pierce the darkness. But quite easily, Frisk spotted where the noise was coming from, which hadn't stopped.
It came from Asriel's bed.
The human child stood up and stalked forward barefoot, until Frisk saw the little Boss Monster's fluffy head, partly covered by a long ear. And the tears that beaded on his sad face, sniffling with sorrow. He was still sleeping.
Discreetly, Frisk slipped into the bed of the little monster who had his back to him. He sat down so that he could face Asriel, and see his face which seemed so fragile. With his sleeve, Frisk dried the wet fur on the Asriel's cheeks, and the other hand grabbed an ear to pet it. Under his fingers it felt like cotton. Asriel would never admit it and protested every time because it made him blush, but the young monster secretly loved when Frisk did it.
His complaints gradually calmed down; Asriel's expression relaxed, sighing happily at Frisk's touch. He even approached the human a little, who covered him with his arm to give him a hug. Little by little, Frisk felt himself falling asleep again, and a few seconds later, he fell asleep for the second time.
Asriel's wounds would likely take a long time to heal, and the prince's nightmares might never end.
But, as long as Frisk could, the child would be there to comfort him every time.