Firefly.

“What’s wrong? Why are you still up?” Marth asks sleepily, rubbing his eyes and stifling a yawn.

“It’s your birthday,” Link informs the exhausted prince in a way-too-excited-for-this-hour voice, “and I have a wonderful surprise for you.”

Link takes Marth outside to catch fireflies for his birthday.
A oneshot at 822 words.

This is for Arianna. Happy birthday.
Link loves her Marth, always.