Hyperdimension Neptunia belongs to Compile Heart, Idea Factory, Sega and whomever else worked on it.

Staring down Arfoire's transformed state, Orange Heart and Purple Sister were both feeling despair settle over them after the transformed Arfoire had attacked them. "Gearsy..." Orange Heart whimpered. "This is it. I'm sorry."

"WAAAAAAAGH!" A loud voice from above suddenly filled the cavern that Purple Sister, Orange Heart and the transformed Arfoire were in.

"Wait..." Purple Sister trailed off and looked around. "Is that... Neptune?"

"Move! Move! MOOOOOVE!" The voice that sounded like Neptune yelled again before a loud crash was heard, filling the area with smoke and dust, causing Orange Heart and Purple Sister to cough from the smoke and debris that resulted from the crash.

"Oww! Oww! Oww!" A voice called out as the smoke started to dissipate and clear up. "Oh man! I really took a tumble there and I was so close to catching a skyfish too!" The smoke revealed a young woman with long purple hair, two black D-pad hair clips, purple-colored eyes, a black hooded parka and black shoes on who was holding a notebook in one of her hands. "Good thing I'm pretty resiliant since the ground disappeared on me and I fell down."

"What?" Both Orange Heart and Arfoire asked stupidly.

Meanwhile Purple Sister was staring at the newcomer intently.

"Oh!" The person smiled at the group. "It's the people who were down below and..." Her smile faded and her face went pale as she looked at Purple Sister. "Ah ehheh hehh... It's been awhile, hasn't it?"

Purple Sister actually frowned and floated over to the new person before grabbing her ear. "You disappear for years and this is the first thing you say to me when you show up, young lady?"

"Owwie! Owwie! Owwie!" The other person cried out, her eyes going white and blank while tears leaked out of them. "Mommy! Mommy help! Auntie's being mean to me!"

"HUH?!" Orange Heart, Umio and Arfoire all gawked in surprise.

Purple Sister sighed and let go of the girl's ear. "Seriously, Neptune, you made me, Plutia and big sister all worried about you when we returned to find you and you weren't there. We searched for a month and even had the guild looking for you."

"I'm sorry." The larger version of Neptune had an embarrassed look on her face. "I really didn't mean to just go and disappear like that, I was looking for bugs and I found this really neat one and then I disappeared."

"Uh..." Orange Heart waved her hand. "Gearsy, is this girl Nepsy?"

Purple Sister nodded. "Yes, Uzume. This is Neptune... My niece."

Neptune gulped as Purple Sister gave her a thoroughly disappointed look. "...I'm grounded, aren't I?"

"Be thankful that I found you first instead of Plutia or Neptune." Purple Sister rubbed her forehead. "Before you ask, Uzume, she's Neptune's daughter."

"Nepsy has kids?!" Orange Heart's eyes were blank white in shock. "When?! How?!"

"Um... Mom was a CPU for six years when I was born." Neptune rubbed the back of her head. "I don't know who dad is, I don't know much of anything else about how I was born, mom doesn't talk about that."

"AHEM!" Arfoire cleared her throat. "As riveting as this is, I'm still going to kill you now."

"...If I help you out of this, will you promise not to let mom punish me when we meet up with her again?" Neptune asked Purple Sister nervously.

Looking at the older girl, Purple Sister sighed softly. "I'll do what I can to keep the punishment to a minimum, okay?" The next thing that she knew, Neptune was hugging her tightly. "URK!"

"Thank you, auntie! I love you so much!" Neptune let go of the hug and turned to face Arfoire. "Alright, listen up, you giant bug! I'm going to beat you up, trap you in my Nep Note and then beg mom not to have aunt Plutie punish me!"

"...You know that we're going to tell her that we found you, right?" Purple Sister said and Neptune's eyes went white and blank from shock.

"NOOOO!" Neptune cried out in terror. "Anything this bug could do pales compared to what aunt Plutie could do to me!"

"Uh..." Orange Heart and Umio both stared in shock.

"THAT'S IT! I'M KILLING YOU NOW!" Arfoire screamed in anger and charged the group.

(-)

After defeating Arfoire and Neptune sealing her into the Nep Note, both Purple Sister and Orange Heart transformed back to normal. "So..." Uzume, now a redhead, "what's going on, Gearsy? Why is there a big Nepsy and what's going on?"

"Well..." Nepgear tapped her chin. "Awhile ago, Neptune was sent to another dimension for years, we mentioned this before," Uzume nodded, "and a few years after she ended up in that dimension, she ended up having a child. The only ones who know all the details are Neptune, the Histoire of that world and the CPU of that nation, Plutia." It was odd too, not even the other CPUs of Plutia's world knew about the circumstances surrounding Neptune having a child. "...And this Neptune's name is technically Neptune II."

"Mom was pretty egotistical," Neptune II sweat-dropped. "Anyway, when you all had to go stop that stupid lady, I went outside to play and chased bugs to put into the Nep Note and found one that looked like Histoire, just with dark skin and caught her."

"...Her name wasn't Croire, was it?" Nepgear asked and Neptune II nodded. "...Well, that explains a lot." She sighed softly. "Boy, you're going to be in trouble when we get back home."

Neptune II sweat-dropped heavily. "Please don't let mom punish me too much, you promised!"

Nepgear smiled and nodded. "Don't worry. I'm sure that Neptune will just be happy that you're alive."

"Um, Gearsy, how'd you know that this Nepsy is your niece?" Uzume asked, curious.

"Oh, I didn't, I was taking a guess." Nepgear giggled as Uzume, Neptune II and even Umio all face-faulted. "Well, considering that she said it had been awhile since we had seen each other, I was pretty sure that she was Neptune's daughter."

Neptune II gulped, wondering how bad her punishment was going to be when her mom caught up to her. "I hope that mom's in a good mood."

(-)

Some time later...

Standing in her Basilicom after helping Uzume out one last time, Neptune stood next to Histoire and IF with a smile on her face and a twitching eyebrow. "So..." She gave Neptune II an annoyed look. "You disappear for three years, appear in front of Nepgear and the first thing you wanted to do when seeing me in that battle was try and run away?"

"...Yes?" Neptune II, who was on her knees in a seiza position, gulped. "Sorry, I was..." She gulped again when Neptune took a step forward and was Purple Heart. "Uh..."

The next thing she knew, Purple Heart was hugging her. "You stupid girl! You worried me half to death! I think I got a few gray hairs because of it." Neptune was waving her arms up and down as her face was buried into Purple Heart's chest. "I told you to stay at the Basilicom while the rest of us dealt with stuff, and I came back to get you and you were gone!"

"MMMPH! MMPH!"

"I'm more interested how Nep Nep has a daughter." Compa spoke up, smiling as Purple Heart's cheeks turned slightly red. "Was it a night of passion with someone that you never saw again?"

Histoire twitched at the thought of Neptune doing something so irresponsible. "Neptune, if you did that, I shall give you such a lecture that you won't..."

"No..." Purple Heart shook her head. "I knew Nep II's other parent quite well." She closed her eyes and transformed back into her human form. "Phew! Anyway..." She opened her eyes. "There's no need to..."

"But who is my father?" Neptune II asked her mother. "You always keep quiet about it and..." She was suddenly cut off by a loud, happy yell and a flying yellow streak. "OOOGH!"

"NEPTUNA!" A young girl yelled and blinked as she looked at who she was sitting on. "You're not Neptuna!"

"Uh, P-Ko..." Neptune sweat-dropped. "What are you doing here?"

Before Peashy could answer, someone beat her to it. "Because, Neppy, it's your daughter's birthday and..." Plutia blinked as she walked into the room. "...Neppy, is that Neppy II?"

"Plutie!" Neptune smiled at her friend. "Yeah, this is my wayward daughter, who came back after three years and Nep Jr. found her."

Neptune II was sweating as she saw Plutia, who had an irritated, but happy expression on her face. "Ah, hi, auntie..." She gulped as Plutia narrowed her eyes. "I'm sorry I was gone for three years! I saw so many bugs that I just had to get them all!"

"Plutia," Histoire spoke up, "while it is nice to see you and Peashy again, we are in the middle of a crisis here. And," she gave Neptune a disappointed look, "to find out that Neptune had a child without the father around..."

"Huh?" Plutia had a confused look on her face for a moment before she realized what was going on. "Neppy, maaaaaybe they should know who Neppy II's daddy is."

"You know, Lady Plutia?" IF asked, being polite as she knew from her other self that it was a bad idea to make Plutia angry.

"Uh huh..." Plutia nodded. "Neppy never let me get AAAAANY sleep when she was pregnant either!" Plutia pouted. "Buuuut I guess I deserved it after what I did."

"What you did?" Compa asked while Neptune's face was turning more and more red. "What was it that you did?"

"Weeeeeelll..." Plutia smiled. "Neppy was talking about Neppy Jr. and how she was such a good little sister and I wanted one myself."

"Goodness, you were saying such nice things about me?" Nepgear asked, blushing hard. "Awww... Thanks, big sis."

"So I asked Neppy if I could have a sister too." Plutia pouted. "But because there's no Sharicite in my world, I couldn't have one. So I asked Neppy if we could make a little sister."

Everyone, except Peashy, who was hugging Neptune II happily, suddenly stiffened and turned towards Neptune, who was blushing so hard that steam was coming out of her ears. "N-Nep Nep?" Compa stuttered. "Wh...What happened?"

"I..." Neptune's blush was atomic at that point and Plutia was giggling. "I only agreed to have fun like that ONE time because Plutie wouldn't stop asking and Plutie used her shares and..."

"Nine months later, Neppy II was born!" Plutia finished for Neptune.

"...I need a freaking drink." IF said as she realized what was going on.

"Wait, so my auntie was my daddy?" Neptune II asked and Neptune nodded. "...Why didn't you tell me, mom?"

"I didn't want to confuse you, okay? I was going to tell you after everything calmed down." Neptune said, her face even more red, if that was possible.

"...I think I'll hold off on that lecture for now." Histoire muttered and floated off. "IF, I'll join you for that drink."

"So..." Neptune II looked at Plutia. "...Should I call you daddy then?"

"Nah," Plutia shook her head. "You can call me auntie still. But you're still in trouble for disappearing."

"Nep Nep..." Compa spoke up. "...How did you make a baby with Plutia?"

"...Shares are versatile things." Neptune said softly.

This one-shot was inspired by an image of Purple Heart and Big Nep on a beach together and someone on Discord going "oh look, a mother and daughter pair" and my mind went into overdrive.