"Hey guys," Phineas said, entering the living room. "Our invention is finished, and we're wondering if you'd like to try it out."

"I knew I was forgetting something!" Candace exclaimed. "You are soooooo busted."

Phineas did not hear that last part (he was always oblivious to the fact that Candace wanted to get him in serious trouble with their mother), so he said, "C'mon, I'll show you. It's one of our best ever," and walked to the back door.

Isabella then noticed, through the glass door leading to the backyard, a mysterious girl she had never seen before, chatting away with the other boys. It was rare that Phineas would know someone she didn't (Danville Middle was a fairly big school, and the gang had made friends with just about everyone there), but it did happen. And it made Isabella concerned that Phineas had a friend who wasn't just a friend.

"Oh no!" Isabella whispered to Candace while Phineas opened the back door. "It seems Phineas already has a girlfriend!"

"Then I guess it's time for lesson five: competition," Candace whispered back. "Try telling Phineas how you really feel, and maybe he'll break up with her. If it turns out the new kid's actually in a relationship with him, that is."

"So sparticles aren't small particles, but supersymmetric partners to conventional particles, and they're a component of dark matter?" Phineas was asking.

"Correct," Susanna replied. "Dark matter is made of more than just SUSY particles, but-"

"PHINEAS AND FERB!" Candace's scream cut her off. "What is that thing you've built?" the sixteen-year-old continued, storming into the middle of the yard.

"It's a device that can find true love," Phineas explained. "We made it in honor of Mom and Dad's anniversary, and we were wondering if we could use you as a test subject."

"Oh, you want to help me find my true love?" Candace asked, suddenly regretting her harsh tone.

"Yes. Yes, we do. In a sense."

"Okay. So how do I work this thing?" Candace said, gesturing to the large machine that stood before her in silence.

"It works by scanning your DNA. Hair is the easiest form to get, but other parts of your body will do too."

Candace decided to go with hair. She plucked an orange strand out of her scalp, wincing as she did so, and gently held it over Cupidtron's scanner, which took up half the control panel. The scanner emitted a green light that swept over the hair, top to bottom. A picture of Candace with a worded description appeared on the left half of the screen. The machine bleeped out "Candace Gertrude Flynn."

The machine let out a whirring noise as pictures of other people flashed across the right side of the screen. There was a click, and the machine settled on a profile with a picture of a tanned blond-haired boy, and the machine bleeped, "Jeremy Johnson."

"My true love IS Jeremy!" Candace cried, ecstatic and blushing fervently. "Now I know we'll marry and have kids named Xavier and Amanda!"

"You left out Fred," Susanna said wryly.

Candace stopped blushing. She turned around to face the girl. "How would you know if I will have another kid? And more importantly, who are you?"

"The princess of Unicornland," Susanna replied sarcastically, somehow managing to keep a straight face. "I'm joking. I'm your niece from the future."

"How did you get-"

"Time travel." Susanna lifted her left wrist to show the white, watch-like device on her wrist.

"That's a time machine?"

"Look, technology's getting more compact than it is now in the next twenty-eight years, alright?"

"So...I take it you're Phineas' daughter? Is that how you know my future children?"

"Yes."

"Now I'm just confused."

"I can tell you how it happened, if you want," Phineas volunteered.

Everyone sat on the ground in a circle. Isabella, who had been quiet since getting outside, asked, "So Phineas, you're not dating her?"

"WHAT?! Isabella, that would be disgusting!"

"Not to mention illegal," Baljeet added. Buford elbowed him in the gut (for obvious reasons). "Ow!"

"My love for Susanna is the kind a dad feels for his daughter, and only that," Phineas clarified. "Why would you even ask that question?"

"Oh, just curious..." Isabella blushed nervously.

"Looks like a certain Fireside Girl's got a crush on a certain young inventor," Susanna said coyly with a little smile.

Isabella immediately slapped her hand over Susanna's mouth.

"Huh?" Phineas asked.

"Nothing...just nothing...heh heh..." Isabella stood up and grabbed Susanna by the arm, pulling the (now standing) redhead behind her to the back door of the Flynn-Fletcher residence.

"We need to talk," Isabella told her.

Behind them, they heard Phineas ramble on about the story of what happened that morning, but they were so far away all they could hear was "Blah blah blah Perry blah."

"This is bad," Isabella fretted. She and Susanna were in the living room. Isabella paced around the coffee table, while Susanna sat on the couch, obviously relaxed.

"I don't see why," the other girl replied.

Isabella sat on the couch next to her. "Look, I really like Phineas, and -"

"I know. The others told me."

Isabella groaned. "I told Ferb to keep his mouth shut, but NO, he has to tell everyone."

"Hey, it was pretty obvious. Even if he hadn't, I would've figured out anyway."

"Not to Phineas. He's completely oblivious to my attempts to tell him how I really feel. And now more so than ever."

Susanna rubbed her chin (she may have a head shaped like a half-circle, but she does have a chin) in thought. Then she spoke up. "Maybe there's something else. What if he does like you, and is trying to make it seem like he doesn't? That has happened before."

"I never thought about that before. I've spent so many nights worrying about whether or not he likes me and I never even considered that."

"How long has it been? Eight years? And you've lost that much sleep? You're practically an insomniac by now."

Isabella gasped. "How did you know I've liked Phineas that long?"

"Because I know THIS."

After making certain they were alone, Susanna leaned forward and whispered something into Isabella's ear. Something that changed Isabella's entire outlook on the redhead.

"I-is that true?" Isabella asked, nervous.

"It's nothing but." Susanna replied, smiling.

Isabella laughed. "I think this is the start of a wonderful friendship."

They high-fived.

AN: You'll have to wait until a later chapter to find out the secret. Review, recommend me on TV tropes, go to my DA page, and stay tuned! ~ T. Nerdinator.