mark and donghyuck were peacefully walking in the streets of incheon.

it had stopped raining, meaning donghyuck wouldn't be transforming as soon as they stepped out of the house. also, as it was his 8thday above the surface, he was walking quite well, still stumbling from time to time, but mark was always here to help him.

mark's uncle had left the day before, leaving mark and donghyuck alone at home, meaning donghyuck could walk around freely without worrying of being caught up.

the two boys were enjoying their walk, stopping every two meters because donghyuck was fascinated about the shop windows. they even entered a toy shop and mark ended up buying donghyuck a pack of 'robot fish' for him to play in the pool.

they continued their outing, stopping at a café that sold ice cream. mark and donghyuck ordered water and ice creams. after minutes, the waitress came with two glasses, a water bottle, a cup of vanilla and chocolate ice cream for mark and a strawberry ice cream for donghyuck. mark had chosen for him since he had never had one.

"how is your ice cream?" mark asked, looking at donghyuck who was devouring his ice cream.

"amazing! why don't we have those underwater?"

mark chuckled. "want to try mine?" he asked, showing his spoon with chocolate ice cream on it to donghyuck.

the merman opened his mouth waiting for mark to make him eat.

mark laughed looking at donghyuck's reaction. chocolate was definitely not his favourite. mark then did the same with his vanilla-flavoured ice cream. this time, donghyuck smiled. "i prefer this one." he said.

mark looked at the boy fondly, chuckling when he saw donghyuck had some ice cream around his mouth. he took a napkin and gently pressed it against donghyuck's lips to brush the ice cream off, making donghyuck flush at the sudden action.

"t-thank you." donghyuck shyly said. "i still prefer strawbeanie!" he exclaimed making mark laugh again.

"it's 'strawberry'! not 'strawbeanie' you dummy!"

"i don't care about its name, it's so good!" donghyuck said, eating a big spoon of ice cream as soon as he finished his sentence.

"don't eat it too quick, you'll..." mark stopped when he saw donghyuck taking his head between his hands. "...have a brain freeze." he finished with a chuckle.

"it hurts." donghyuck whined.

"here. drink some water." mark said, pouring water in donghyuck's glass.

the merman grabbed the glass and drank some water, scrunching his nose at the strange taste. "something is missing." he said looking around the table. he found in the small table basket a sachet of salt that he opened and emptied in his glass, under mark's widened eyes. donghyuck mixed it with his spoon before taking a sip again. "way better now!" he said before drinking a good amount of it. "want to try?" he asked looking at mark.

"huh, thanks but i'll pass." mark replied.

"it's rude. i did taste you disgusting brown ice cream!" donghyuck whined, making mark roll his eyes.

"here." he said grabbing the glass of salted water. "i'll try it." he added before swallowing the remaining liquid.

well, he shouldn't have done that.

as soon as the liquid entered his mouth, he felt the way too salty taste invade his taste buds, making him spit everything he had.

long story short, donghyuck was sitting facing mark, and soaking wet.

realising what had just happened – and most importantly, what was about to happen – mark rose to his feet and pulled donghyuck towards the bathroom, praying that no one was in there. under the eyes of the dozens of customers, mark and donghyuck locked themselves in the bathroom just in time. as soon as mark locked the door, donghyuck's tail appeared, making him fall into mark's arms.

"i-i'm so sorry donghyuck." mark said, making donghyuck chuckle.

"you scared me. how could you react this quick?! i had totally forgotten i was about to transform!"

mark looked around the room, and noticed they were in the women's bathroom actually because there was a changing table for babies near him.

with the hand that wasn't around donghyuck's waist, mark pulled the changing table open and sat donghyuck on it.

mark took his shirt off and started rubbing it against the other's red tail.

"what are you doing?" donghyuck asked, eying mark's chest.

"drying your tail, so that your legs reappear." mark explained.

"oh, yeah!"

donghyuck pulled on the hem of his shirt to dry the salted water droplets that remained on his face and in his hair.

and in the spawn of minutes, donghyuck got completely dry, making his legs reappear. the boy jumped of the changing table and rearranged his hair.

mark opened the door, finding himself face to face with a lady in her mid-forties with a disgusted look.

"you shouldn't do these kinds of things in the bathroom of a café, young boys! and especially in the women's bathroom! there are hotel for this! control your hormones!" she protested as a flustered mark grabbed donghyuck's small hand and pulled him out of the place, ignoring the judging looks of the people inside the place.

"what was she referring to?" donghyuck asked when they were walking on the streets again.

mark stopped in his tracks and got even redder.

"it's h-hum... nothing important."

"really?" donghyuck faced mark. "why are you this red then?"

"yes, donghyuck. it's not important." mark said, starting walking again.

"are you sureeee?" donghyuck jumped in front of mark.

"yes donghyuck."

"please, tell me. if it's not this important!" donghyuck whined.

mark sighed. "you're not going to stop asking me, are you?"

donghyuck shook his head with a big grin. "never!"

mark sighed again, rubbing his nape. "she was referring to sex."

"oh, okay." donghyuck said flatly before walking beside mark again.

after a minute of silence, donghyuck spoke again.

"what is sex?"

ψ

mark and donghyuck had made it to mark's house safely.

they had spent the rest of the day alternating between playing in the pool and watching tv.

right now, mark was preparing dinner while donghyuck walked around the house, inspecting the different pictures hung on the walls.

"you live with your uncle only?" donghyuck asked looking. at a picture of young mark and his uncle near the sea.

"yes." mark replied from the kitchen. "i used to live with my aunt as well, but she... she died." mark explained.

"i'm sorry. i shouldn't have asked." donghyuck said, walking to mark.

"don't worry. it was in the past." mark shrugged.

"you don't have any siblings?" donghyuck looked at what mark was cooking.

"no." mark answered simply. "what about you?" he asked after a while, locking eyes with donghyuck.

"me?"

"yes, you. do you have siblings? and who are you living with?" mark clarified.

"oh. i do have lots of siblings. but i don't know all of them." donghyuck explained.

"how so?"

"you know, to reproduce, female mermaids release their gametes which are eggs, and mermen release their sperm on them, which fertilizes the eggs. so, basically every mermaid has tons of siblings."

while listening to donghyuck's biology class, mark pictured everything on his mind, causing him to let go the spatula he was holding. this woke him up from his daydream, allowing him to push these images out of his mind.

"great." he said, not wanting to hear more about it. "who are you living with then?"

donghyuck smiled. "i live with my best friend. his name is renjun. look!" donghyuck took his necklace off, opening the shell to reveal a picture of two boys hugging, one red-haired and one fair-haired. "this is renjun." donghyuck pointed at the fair-haired boy. "he is a mermaid like me. he has a green tail. i love him so much. he's basically the only friend i have."

"you're cute." mark said bluntly, making donghuck's face become as red as his hair.

"aww! stop blushing!" mark pinched donghyuck's cheek, making donghyuck all shy. "you're so cute i want to wrap you in a blanket and cuddle you till you die." mark told, fanboying over donghyuck.

"shut up." donghyuck snatched his necklace from mark's grip and put it back on. "can i eat?"

"sure." mark replied. "there are salmons and tunas in the fridge."

donghyuck opened the fridge and grabbed a tuna before standing next to mark while taking bites on his fish.

a comfortable silence had taken place between the two, the only noise coming from the food heating in the frying pan. however, donghyuck had to break this silence.

"you still won't tell me what sex is?"

mark sighed for the nth time of the day.

"for the last time, donghyuck, i won't- "

mark was stopped in his words by the doorbell.

donghyuck and him exchanged a panicked look before mark told donghyuck to get to his room as mark was heading towards the door. mark opened the door, thinking about who could come at that time of the day, and what he saw made him gulp.

"are you ready to spend the best 10 days of your life?!" a dolphin-like voice yelled.