Moonlight filtered into the small kitchen of Evie's house, casting a soft glow over the two figures inside.

Evie and Zac had been sitting at the table for several minutes now, both starring at the tiny blue potion bottle before them.

The object, which was no bigger than Zac's pinky finger, seemed so harmless. So small and insignificant. But both of them knew that its contents could have a profound impact on both of their lives.

If Evie drank a few drops of the magical liquid, she would be human again.

The spell of the moon pool would be irrevocably reversed, and she could live the normal life that she had always envisioned.

Zac knew that should have predicted that they might be in this position one day. Mimmi had mastered many powerful potion recipes and she had nearly managed to take away Evie's tail back when they had all first met. It was really only a matter of time until his sister figured out a way to reverse the moon pool's magic.

It made sense and yet, for whatever reason (denial? false hope?), Zac had not spent much time considering the possibility that what had happened to Evie could be overturned. Mimmi's first attempt to help his girlfriend had failed, and every effort the mermaids had made to make him human during the past year and a half had also ended in disappointment.

Secretly, he had thought that they had all moved beyond that phase. Evie had seemed to enjoy her time in the ocean and thought that he had taught her how to cope with the new hazards that her life entailed.

He had thought that she was relatively happy with the status quo.

He had thought that she was happy to swim at his side…

But, unbeknownst to him, Evie had encouraged Mimmi to continue on her quest for an anecdote. He had been upset when he had discovered this plot—and frankly, he still wasn't thrilled about the situation- but during the past several days, Evie had tried to make her case.

Apparently, this was what she wanted.

She wanted to live without the fear of exposure. She wanted to stop lying to her dad. To go away to college, be a designer, feel comfortable in public…

She wanted her old life back.

And Zac did not want to deny her that.

He just hated the fact that they would never again share the same bond that they did right now.

With a sigh, the boy ran a hand through his dark hair and tried to muster a smile.

As if sensing his trepidation, Evie reached out and placed her hand on his before taking a quick glance at the clock.

Mimmi had said that, to ensure success, the potion had to be consumed at the stroke of midnight

"Only five more minutes." She said softly, looking down at the table to avoid her boyfriend's gaze.

Zac could tell that she was nervous about what lay ahead but he could also see the determination on her face.

"You're sure about this."

It was more of a statement then a question, but Evie nodded anyway.

"I am." She said softly, still looking away. "And I'm sorry."

They had, of course, talked it all through before. He took some solace in the fact that she had not taken the decision lightly and seemed genuinely sad about what she would be sacrificing. But, at the end of the day, this was not who she was meant to be…this was not her world.

There was nothing he could do to change that.

"Don't be sorry," Zac replied, trying to keep his voice as calm and neutral as possible. As much as it pained him to think of the ocean without her, he did not want to manipulate her into making a choice she would regret.

No matter what happened that night, he still loved her—and love meant putting the other person first.

"You're human. You were never meant to be a mermaid." He paused, trying to ignore the wave of regret that had suddenly surged within him. "I don't blame you for taking this opportunity. I just…I just wish I could say the same things about myself."

"Oh Zac." Evie whispered, her hand grasped tightly around his.

She finally looked back towards him and he could see the well of emotion in her eyes. She knew that his own situation was what made this particularly difficult for him.

Although he had done his best to accept the shocking truth about his origins, he had not fully overcome the conflict and anger within him. He wasn't sure if he ever really would. It had been nearly a year since that fateful night in the merman chamber but Zac had felt torn ever since.

He had grown up on land, thinking he was no different than everyone around him. Thinking that he belonged with his parents…and that his fall into the moon pool had been nothing but an accident.

But then, in an instant, he had discovered that his entire life had been a lie. He wasn't human, his mother had left him, and he had a long-lost sister.

He had always been a merman…and he always would be.

It had completely stunned him, and he had been angry for several weeks after that night—but, in retrospect, it explained a lot.

As soon as he had gained his tail, he had begun to feel more invigorated and contented than he ever had before. Sure, there had been conflicts with the mermaids and drama surrounding the trident—but when he was alone in the sea, swimming faster than he had ever dreamt possible, he had finally felt alive. He had finally felt like himself.

That's why it had surprised him, initially, to learn that Evie did not adjust to her new life in the same way. They had spent many hours discussing it when she had first changed, and Zac could not understand why she did not feel the same deep connection to the sea. Sure, she liked swimming—but she didn't crave it. She didn't feel the call of the waves, and she didn't feel anxious or dry when she stayed out of the ocean for a day.

And she had never really gotten used to her new form.

But, as they now knew, that was because they were fundamentally different.

Evie was a land girl who had been turned into a mermaid.

Zac, on the other hand, was a merman through and through.

He hated to admit it, but Mimmi, Lyla and the others understood him in a way that Evie never had…even after she had gained a tail.

"I won't let this change us." Evie stated, her eyes still full of concern. "We made this work before I turned, and we will make it work again. I know we will."

Zac did his best to smile. She had made similar proclamations during the past few weeks and he had tried very hard to make himself believe it. But a small part of him struggled to match her confidence.

It wasn't that he didn't have faith in their relationship. He knew that they loved each other and that they had overcome many obstacles.

It was, nevertheless, difficult to picture spending his life with someone who couldn't share his experiences. Sure, her time as a mermaid meant that she would always understand him more than most land girls, but he wondered if that would be enough.

Ever since he had learned the truth, and started to accept his fate, the pull of the sea had gotten even stronger. He had been spending as much time in the ocean as he could and, for the most part, his time on land had felt a touch unfulfilling.

He worried that the merman within him was growing stronger and he wondered if he might one day come to accept that as his natural state.

Zac did not want all of his moments with Evie to feel unnatural.

But he feared it might one day reach that point…

"I know we'll figure something out." He said, wishing that he was more convinced by his own words.

He wanted to believe it.

He had to believe it.

That was the only way he would be able to cope.

"Plus who knows," Evie began cheerfully. "Maybe Mimmi will find a way to turn you back one day too. Maybe she'll find a way to alter the potion."

Zac knew that she was trying to be helpful and reassuring, but he could not hold back a grimace. She had meant no harm, but he could tell from her voice that that was what she wanted.

No matter what she claimed, deep down, she still wanted the Zac she remembered.

The Zac who hadn't had a tail, or a magical destiny.

The human Zac.

And he could not ignore how much that stung.

That version of himself no longer existed. And it never truly had.

"That isn't going to happen." Zac stated plainly, trying to mask the pangs of both sadness and anger that he now felt. "The potion reverts people to their natural state. Permanently." He paused and drew a deep breath. "This isn't my natural state." He said, gesturing towards his legs. "If I drank that, I'd be a merman forever. That's what I am, Evie. I don't have a choice."

Zac could feel his heart rate increase as he spoke but he attempted to keep his breathing as steady as possible. He didn't want her to know how this pained him—not when she had made up her mind so clearly and was minutes from what he knew she wanted.

Part of him wished that things could be simple once more too. In some ways, ignorance had been bliss, and the first few months of their relationship had been gloriously normal.

But that would never be the case again. He was certain of that.

Despite the fact that his mother's spell had hidden his tail for sixteen years, there was no going back for him now. That had been some seriously powerful magic, and Mimmi and Rita had explained that it was only possible to cast such spells on children—it would have worn off when he turned eighteen. Unbeknownst to him, Zac's "normal life" had always had a time limit. The moon pool had just speed things up by a couple of years.

"I'm sorry Zac, I didn't mean—" Evie began, her face etched with worry.

"It's fine." He cut in with a soft smile.

For a second, he found himself wondering what he would do if he had a choice. There was no doubt that he hated his lack of control over the situation—it had been fun to be a merman when he thought it was an accident but the realization that it wasn't had made things suddenly more real. It would have been nice to have options. To have a choice.

He still felt best when he swam through the open ocean, but the comfort of that was still out of sync with his self-perception. After sixteen years of obliviousness, it was hard not to see himself as a land boy.

But, while a part of him would always yearn for his old sense of normalcy, Zac knew that he would never feel complete if he was trapped in human form.

It would take him more time to fully come to terms with it but, deep down, he knew that this was who he was.

And Evie knew who she was too. That was why he couldn't stop her.

Wouldn't stop her.

It was time to let her return to her world.

As if on cue, the clock let out the first of twelve rings. Both Zac and Evie nearly jumped out of their seats, clearly on edge about what was to come.

Zac drew a shaky breath.

"You can do this." He said gently, giving her hand a reassuring squeeze.

The girl nodded quickly before reaching out for the tiny bottle. As the sixth chime sounded, she uncorked it and raised it towards her lips.

"I'm sorry Zac." She whispered, her blue eyes briefly locking with his brown. "I love you."

With that, she tipped the bottle forward and consumed its contents.

Silence fell over the room and Zac watched as a pale blue glow surrounded his girlfriend, lifting the spell that had temporarily made her a part of his world.

Deep down, he already knew that this was the beginning of the end.

She was human.

He was a merman.

It had never been meant to be.

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A/N—Let me know what you think :) Hope it wasn't too depressing. I actually did like Zac/Evie in season 2 (she wasn't such a likable character in season 1)—but I wanted to explore their possible divides.