The next day wasn't all that smoother. It started with something wet and squishy as Phineas rose to a wake. She squirmed a bit, trying to understand what it was. It was right between her legs.

'Did I drink too much water?', she wondered.

She sat up, got dressed, and looked back at the bed, wondering if there was a wet spot. Perry suddenly woke up as he was flung off while Ferb suddenly bolted upright in his bed as Phineas screamed.

"What?! What's wrong?!", the boy asked in shock.

"I'M BLEEDING!", Phineas said, her face turning white.

Ferb looked over in fear and saw the red spot stained into the sheets. Candace quickly joined them and when told what was happening, paused for a moment. Very slowly a wide, malicious grin creeped across the older sister. Snickers began to escape then chuckles. Then giggles and it quickly evolved into a loud fit of laughter. Candace backed up to a wall for support, pointing a finger at Phineas and laughing hysterically.

"OH-! MY-! GOSH-! YOU-! IDIOTS!", she gasped between laughs.

"What?! What it's not funny!", Phineas said, tears quickly coming to her eyes. "I'm scared to death!"

"Phineas! You're on your period!", Candace finally said when she forced herself to calm down.

Ferb's shocked expression became ghastly and Perry observed the blood more closely.

"How-?", Perry began to ask.

"Phineas, your invention. What did it do?", Candace asked as Phineas scratched her head.

"It... It changed your physical body into anything.", she admitted. "Animals. Plants...the other gender."

"There you go! You were physically changed into a girl. Thus your body's now functioning like one!"

"But I've only been a girl for one night!"

"That's all it takes I guess!", Candace shrugged, chuckling some more.

Phineas looked at her sister, looked at the blood on the bed Perry was now attempting to clean with a wash cloth, and then back at her.

"Candace... What IS a period?", Phineas asked.

"Ah... Um...", Candace trailed a bit, looking over at Ferb.

The adult knew what she was about to get into and left the room in politeness, asking Perry to follow. Once alone, Candace continued.

"Phineas.. You know girls are where...kids come from, right?", Candace asked.

"Yes?"

"Well this is what happen when there aren't any kids to have.", Candace explained.

It took Phineas a moment to understand but when she did, she gave a confused expression, looked at the stain, and then looked back at her, still puzzled.

"That's not entirely blood. Part of it is... I can't believe I'm gonna give you this talk.", she shook her head with a smile.

Once the discussion had been closed and Phineas came to an understanding, she did as told and went to the bathroom and showered, changed her clothes, and came back out, trying to get comfortable.

"It feels like I'm wearing a diaper...", she said dismally as Candace sat the plate of eggs in front of her.

"T-M-I.", Ferb said, reading his book as he ate.

"Sorry!", Phineas said, feeling herself almost ready to cry.

"Phineas. I'm just saying, I'm still a boy. I don't really WANT to know much about this process.", he said.

"I know! I'm sorry! I-I don't know why I'm crying!", she said as tears came forth.

"Hormones!", Candace said. "And they are in an uproar after being held back by your boyish brain for the last year! Ha ha ha!

"I hate this! I hate this so bad!", Phineas wept, crossing her legs again in pain. "I'm cramping, I can't control myself, and I'm bleeding! How can girls stand this?!"

"You get used to it.", Candace chuckled. "It's life, Phineas. It's a girly girl's life."

When breakfast was done and cleared, Isabella was already the first one to arrive.

"Phineas! Are you alright?", she asked as they hugged. "How come you guys aren't working on the machine?"

"Cause I...", Phineas grew quiet and decided to whisper it in Isabella's ear.

"Oh! Oh my gosh!", Isabella exclaimed, backing up a bit.

"Which is why we can't work on the machine. We're kinda worried something might mess me up.", Phineas explained.

"So you're stuck as a girl for the WHOLE week?!", the friend gaped.

"Yeah.."

"B-but what about, your dad? Your parents?"

"Mom called earlier saying she and Dad are staying for a bit longer, fortunately enough. They're still looking for one of their antiques. But MY dad.. I don't know what we're going to do about that..", she scratched her head worriedly.

"Oh, gosh.. Are you cramping?", Isabella asked.

"Yes! And geez this hurts!", Phineas groaned. "Does it always hurt like this?"

"Only for the first day. Sometimes longer, but mostly just then."

"Well at least it's only for the day."

"HE'S HERE!", Candace yelled excitedly as she zoomed from upstairs to the porch. "Aha ha ha ha ha! When Dad sees what happened to you- OH MY GOSH!"

Candace bounced excitedly while she watched the purple truck pull up to the driveway. Heinz stepped out, a bit surprised to suddenly be greeted by Candace so enthusiastically.

"DAD! Quick, Dad! You gotta see Phineas!", Candace said as she rushed over the moment he got out.

She began to pull him on the sleeve but Heinz pulled back a bit saying, "O-okay Candace! Sheesh, nice to see you too! Just hang on a second, lemme get my tool box, okay?"

"NO! You gotta see it NOW!", Candace whined as Heinz searched through the junk behind his seat. "Daaaddeee!"

"Just hang on a second, Candace!", Heinz said, finally pulling it out. "For an 18 year-old girl, I would think you would've learned to calm down by now!"

She quickly pulled him inside, excitement coursing through her body. But as they entered the house, she looked around to find the living room was empty.

"NO! Where's Phineas?!", Candace snarled as she looked about while her dad sat the box down, glancing about with equal curiosity.

She ran into the kitchen, shouting for Phineas when Heinz peeked up the staircase to see Isabella, Ferb, and Perry at the top, crowding around a door.

"Um..", he managed to say with a point before Candace was already up at the top.

He shrugged and followed as Candace tried to wrench the door open.

"PHINEAS! Get out of the bathroom!", She growled.

"Candace, I don't think that's gonna help.", Isabella said, trying to back her up a bit.

"You can't hide in there forever woman!", the sister continued to shout.

"Candace, please. You don't need to insult your brother like that.", Heinz rolled his eyes as he reached the top of the stairs. He came over and knocked on the door. "Phineas? It's Dad. Why are you hiding in there?"

There was no reply in fear that Phineas' new voice would give Heinz the idea. Candace tapped her foot impatiently though still smiling. She was DYING to see the reaction when the moment finally came. It only took a matter of patience.

"...Phineas. Come on now. You're acting like a little kid.", Heinz groaned, making the young girl shift uncomfortably in the bathroom. "...Welp. I guess that's it then. You're not coming out. Candace certainly doesn't wanna spend time with me. I guess I'll just..head back to the DEI. Invent and discover things...all by myself. With no son to bond with."

He started to walk away but paused at the stairs, waiting. There was a small click and he turned around with a sly smile.

'Gets them every time.', he thought to himself as he came back over.

The door slowly opened and Heinz's eyes grew wider and wider as the young girl stepped out, looking nervously at the floor. She gave a sheepish grin back up at her father.

"Um... I had...a bit of an accident..", she admitted with a slight chuckle.

The man continued to stare as Candace watched, amazed with his facial reaction, waiting for sound to burst forth. But Heinz only continued to stare...and stare...and stare.

"...Dad?", Phineas asked, feeling slightly concerned.

The man's eyes closed as he suddenly fell over backwards, being quickly caught by Ferb and Isabella.

"DAD!", Candace and Phineas both exclaimed, though Phineas was more frightened.

After helping lay the man on the couch downstairs, Phineas sulked in a corner, feeling rejected and ready to burst into tears at her father's reaction. Isabella tried to console her.

"He hates me! Why else would he act like that?!", Phineas sobbed.

"He doesn't hate you!", Isabella said, trying to sound hopeful. "He was just...surprised."

"But he's never passed out before! Not like that! Not because of me!", Phineas continued.

"Oh Phineas, get over yourself!", Candace groaned, rolling her eyes. "I know you're on your period and you're an emotional wreck, but that doesn't mean you have to bawl at everything."

"And you've been so mean to me since this all started!", Phineas only cried more.

"Candace..", Isabella began, implying that it was probably best to leave the young teenagers alone.

"I'm just saying!", she said, raising her hands in mock defense. "But, who cares, right?"

She headed off to check on her father as Phineas continued.