Here's an idea that I had as I was rewatching the show. It's a one-shot so do not expect me to create a story after it. Anyway, hope you enjoy!

Zac stood in front of the door to his house. No, parents'. No, adopted parents' house. He had just stormed away from Rita's and up to the door. He planned on barging in but now it just didn't seem like the right thing to do. Should he knock? No, that would make things more awkward than needed. He just opened the door and walked in.

"Zac?" His mother's voice called from the kitchen. No, his adopted mother.

Zac didn't answer but walked in that direction. He really didn't trust his voice right now.

"Zac?" Her voice was filled with worry and she walked out of the kitchen.

Zac leaned against the archway to the kitchen. She quickly walked over to him and started fretting over him.

"Zac? Zac, where have you been? We were so worried. Zac? Zac? Are you okay?"

"I-I'm fine mo…" His voice died on the word.

She frowned. "Let me go get your father. He might know if you're sick or not. We'll meet you in your garage, okay?"

She turned to leave but Zac grabbed her elbow. "M-mom. Am-am I adopted?" He stumbled over the words.

Her face morphed into one of surprise and worry. "I'll go and get your father Zac."

He nodded and watched her quickly walk up the stairs then disappear to the second floor. He walked out the back and headed to his garage. He hesitated before opening the door and collapsed onto the light green couch. Waiting. What would they do? Deny that he was adopted? Or would they cry and beg for him to forgive them?

Knocking shook him out of his thoughts.

"Zac? Are you in there?" His mother's voice came from behind the door.

"Can we talk?" That was his father.

"Yeah, come in." He called back.

His parents walked in and took a seat on the other couch. Silence surrounded the family.

"So Zac, how have you been?" his father asked, trying to break the silence.

Annoyance and anger bubbled in Zac. How could he just ask a simple question when something much bigger was what needed to be answered!

"I don't know how I've been bacue I just recently figured out that I might be adopted and everything I've been told might be a lie and-"

"Zac." His mother gently cut him off. "You're confused and upset. We understand but know that we love you know matter what happened."

"So…"

"Zac, what you're mother is trying to do is answer your question." His father said, placing his hand on his wife's.

"You asked if you were adopted Zac and the answer is yes." She looked at Zac, tears beginning to form. "We were going to tell you once you were old enough but I, I got scared of what might happen. We planned on telling you when you were ten. Then it was fourteen. Then it was eightteen. And I almost decide not to tell you at all because-"

"Lauren, we can tell him that part later." Zac's father told her.

"What? What part?" Zac looked between them. "Can I at least get a full truth for once in my life?"

"Zac, we-we can't tell you the other part. You would never believe us." His mother informed him, a few stray tears running down her cheeks.

"I don't care if I'll believe it or not, I mean I already have enough crazy stuff in my life, just as long as I get the truth!"

"Do you remember when you were growing up we used to tell you how special you were? How worried we'd get if you came home with a runny nose or a scraped knee?"

Zac nodded, confused as to where his father was going. He did remember those things. They eventually stopped but it had annoyed him for the longest time.

"That's because we weren't sure at first of how to care for you. You aren't like us Zac." His father fell silent from there.

"Zac, you're not human." His mother whispered.

"You, you knew? You knew all this time and never even thought to tell me? I was surrounded by people-"

"Wait you're saying you knew you weren't human?" Zac realized that they thought he was getting new information.

"Well, I-uh… What am I then?" He asked, nervously trying to cover himself.

His adopted parents looked at each other then at Zac, completely serious. "You're a merman."

His breath hitched. They knew. They had known all along. And yet they never told him. Even when it was obvious he was spending more and more time in or around or being wary of water.

"Zac? We're sorry we never told you and we understand if you don't believe us but it's all true. And-"

"Mom," He whispered. "I know."

The tears poured down her cheek as she got up and hugged him tightly. His father follow suit afterwards.

"I have a couple more questions though." Zac said, struggling out of the hug. His parents released and sat back down.

"Go on then." His father probed, after Zac didn't say anything.

"Well, um, did you… did you ever know my birth parents?"

"We knew your mother. She had saved me from drowning once and Rob was curious as to who my mysterious friend was. We didn't see her for a long time after we got married until we were walking on the shore at night. She was panicked and held another baby, besides you, in her arms. She somehow knew that we couldn't have a baby of our own and asked us to raise you. We gratefully took you and reassured her that we'd take good care of you. And you've been with us ever since." His mother explained.

"So you never knew my birth father?" Both of them shook their heads. "And who was the other baby?"

"Your sister. Your birth mother had told us that she'd be safe with another pod since she was a girl but you had to stay with us."

Zac was overwhelmed. It was all too strange and incomprehensible. He was still getting over the fact that Mimmi was his sister, his parents weren't his parents, and now he had to deal with his parents actually knowing what he was. Zac held his head in his hands.

"Zac, we have a question of our own." His father said. Zac lifted his head. "I know you're trying to wrap your head around all of this but can we ask this one question?"

"Sure." Zac tried to kept the sarcasm back.

"How did you figure out you were adopted?" His father gazed curiously at him.

Zac opened his mouth and closed it again. Two more times he did that, unsure of how to answer. Finally he decided a simple sentence would hold them over until he could talk with Rita and Mimmi on how to answer that in the best way.

"I met my sister."

His parents mouths gaped. "When… How? She…"

"Great, make it more complicated than it already was, why don'tcha?" Zac muttered under his breath.

Knocking on the door startled all three of them. "Zac? You in there?"

Zac shot up and stumbled over to the door. "Ahh, Evie! I'll be right there!"

"Zac? But I'm not-"

"Shush!" He hissed as he opened the door. "What are you doing here?"

"Checking up on you! You aren't the only one going through problems!"

"Can we please discuss this outside?"

"Probably better here. You're more comfortable in here anyway."

Lauren and Rob were trying to see who was at the door and understand what was going on but Zac's head blocked the person's head and the conversation was very confusing. Then Zac pushed the person back and closed the door behind him. All they could do was listen.

"Why don't you just leave me alone?"

"Because it's better when you have friends and family to help you through hard things."

"You read that somewhere didn't you."

"Shut up! It's not like you know everything!"

"And neither do you Mimmi!"

"I at least know who you are Zac! And as your-mmph!"

Zac's hand muffled her next words. "My parents are in there!" He hissed.

"Oh good. Someone is helping you."

"Like you care."

"Of course I do! I'm- murupmh."

"Look I'm trying to keep things-ew! Yuck! Mimmi!"

"Then stop doing that! Your hand tastes disgusting!"

"Did you have to lick me to make your point?"

"Yes. Yes I did."

"You could have at least- whoa!"

A sound, almost like a bunch of chimes, tinkling, and jingles all together, was heard then a loud thump and shlop.

"Zac are you okay?" His mother called.

"I-uh, I'm fine mom!" He called back. He sounded rather panicked though in his parents' opinion.

"Oh my goodness! I didn't realize that-"

"Well then help me Mimmi! You got me into this!"

"Actually, you could blame this on-"

"Zac? Are you sure you don't need help?" His dad called this time.

"R-really! I'm good!"

Rob and Lauren glanced at each other before getting up and walking to the door.

"We're coming out, okay Zac?"

"Ahh. No! Not okay! Mimmi hurry up!" Zac was panicking now.

Rob turned the handle and opened up the door to see Mimmi and Zac with a coat on his legs. Well, the place where his legs should be. Instead there was a blue scaly tail. On her knees next to Zac was Mimmi who had been frantically trying to dry her brother off. Mimmi and Zac were frozen in fear, their expressions practically identical.

"You aren't Evie." Was the first thing Zac's father commented on.

Zac's mother kneeled down and ran her hand over Zac's scales. "This is why you asked us, isn't it?"

Zac glanced at Mimmi giving her a see-what-I-meant look.

"Okay, okay. My fault." She told him.

"Yes now help me explain this Mimmi!"

"You could always tell them the truth." She shrugged.

"And then what?" He shot back.

"Zac, you demanded the truth from us. I think it's only fair that we get the same." His father told him.

Zac scowled and muttered, "Forgot you were there."

"And who is this girl who is obviously not Evie."

Mimmi seemed to decide that was her cue to introduce herself. "I'm Mimmi. Zac's-"

"Friend. She's a friend." Zac cut in.

His mother raised an eyebrow. "Really?"

Both nodded vigorously. Then Zac's tail vanished and his legs and clothes appeared once again.

"That was a little late wasn't it." Mimmi commented.

"Yes it was Captain Obvious." Zac remarked, getting up.

"Who's Captain Obvious?" Mimm asked.

Zac groaned. "Are you serious?"

"Yes I'm serious. What do you think I am?"

"I could list a few things. Would you like that?"

"Sorry to interupt but we'd like some answers Zac.

Zac sighed. "Come one Mimmi. You're going to suffer as well."

"Not cool Zac!"

"You got me into this, you help me get out." Zac told her and walked back into his garage.

Mimmi muttered angrily but followed. So the parents of Zac sat on one couch and the two mersiblings on the other. An awkward silence surrounded them all until his mother spoke.

"So. You have a tail. And you didn't think about telling us, why?"

Zac remained silent, staring at his shoes.

"Zac! Answer me!" His mother was raising her voice.

"Why do you think?" He muttered.

"Zac! At least be kind to them." Mimmi scolded him.

"Who says you have the right to but in? Because last time I checked, no one said so."

"You asked me to help you, so I'm going to help."

"Then I was mistaken. I'm good."

"You know, she didn't only leave you."

"Oh wonderful. How reassuring." Sarcasm dripped from that sentence.

"Stop throwing yourself a pity party Zac! Nerissa left me too! I barely remember her!"

"At least you remember and knew her!"

"Shut up! I'm trying to help you! Like a sister would! This is strange to me too Zac."

"And I never asked for a sister! I never asked for any of this! I just want it to go back to the way it was!"

"And never know who you really are? And leave me alone in the world? How selfish are you? You have two caring parents while all I have is a cowardly pod and a makeshift one that can break apart any moment! Then I find you and you hate me! Fine! Hate me! I'll leave and things can go back to being the ignorant, stupid, land people 'normal' you love so much!"

Zac opened his mouth to retort but his father stopped him.

"Zac, is this the sister you mentioned?"

Zac and Mimmi were glaring at each other.

"Zac Blakely!"

Zac whipped his head around to look at his adopted father. "What?"

"Explain all this from the beginning right now. With the help of Mimmi."

Zac reluctantly explained his side of the story, Mimmi filling in any gaps. Then Mimmi told his parents her side with Zac commenting here and there. By the time they were finished it was getting dark out and Mimmi was still curious as to how the Blakelys were going to deal with having a merman for a son. So she asked them and they told her their story, taking turns because dinner needed to be started. By the time they were done, it was 9:00.

"Mimmi don't you have to meet up with Sirena and Ondina at the Moon Pool?" Zac asked her.

"Yeah, I guess." Mimmi replied. "Your parents are super nice Zac. You're lucky."

Zac smiled a bit and nodded. Mimmi smiled back and walked away from Zac's garage to the dock. He saw his mother run out and talk with Mimmi quickly, somehow making her smile brighter than before. He turned away and walked back into his place, collapsing onto his bed. His phone buzzed and he picked it up to see who'd messaged him. It was Evie.

'Hey, I wanted to check up on you. Are you okay? Did you talk to your parents?'

Zac knew the perfect response now that the truth had come out.

Horrible ending I know. But I might fix it if I have an idea for a better ending. Hope you enjoyed!