Setting details and ages: my assumption is that Phineas's birthday in the Clip-O-Rama is his 11th; Isabella's birthday is earlier in the year, Ferb's is later, and they're all in the same class year. This takes place 4 years later, beginning of summer, so Isabella is 15 while Phineas and Ferb are 14.

Isabella awoke to her alarm clock going off at 6:30am. She rolled out of bed and silenced the alarm on her way to the bathroom before realizing that she'd forgotten to turn it off; today was the first day of summer vacation, and she could have slept in. Darn. Now I'm awake. And I was having such a nice dream about Phineas, she thought. He'd just told me that he'd always loved me and couldn't hide it anymore, and wanted to be with me forever.

Freshman year was over, and she had just turned 15; Phineas's 15th birthday was coming up soon. She'd been head-over-heels for the tall red-haired boy across the street for almost half her life, and yet he still seemed oblivious. He liked her, that much was obvious, and she'd noticed that he didn't treat her just as a friend, but he never opened the door to any more than that.

And I don't push the issue, because he might say no. And so I try to hide my feelings and never force him to make the decision. I'd rather have 'maybe' forever than risk a 'no'.

Well, maybe he'd finally make the first move this summer. Presumably he had another summer of great things planned. Maybe one of them was announcing his undying love for the Mexican-Jewish girl from across the street.

A more cynical part of her brain said, It's more likely he'll fly to the moon. Again.

Ferb wandered down to breakfast to find Phineas already there, glaring at a piece of paper as Perry ate Purina Platypus Chow in the corner.

"Can you believe this, Ferb?" Phineas said. "They gave us homework. Over the summer. That's just wrong. It's going to be impossible to do anything creative with this hanging over our heads."

Ferb considered. "Perhaps we should get it done, then, so we don't have to worry about it any more."

Phineas sighed. "I suppose. That feels wrong, too. Like we can't even enjoy our summer vacation yet. And besides, everybody will be coming over here, expecting us to have something cool in store. How lame will it be to say, 'Sorry, we're doing homework today'?"

Ferb kept silent. He knew his step-brother would figure out the right answer to just about everything, given a little prodding and some time. Everything except his relationship with Isabella, I suppose. Eventually he's going to have to come clean about how long he's known she likes him, and how long he's liked her.

Sometimes I just want to lock the two of them in a room together and not let them out until they figure this out.

Phineas sat up. "I think...we can't solve this one on an empty stomach. We'll figure this out after breakfast."

Ferb nodded and got two cereal bowls.

Phineas sat with his brother under the big tree in the back yard, staring at the paper.

Ferb said, "It hasn't changed."

Phineas sighed. "I know. It's just...the reading assignments are fine, we've read most of them anyway. It's the history paper I'm worried about. 'Choose a time and place in history; write a three-page paper describing the daily life of a typical person of that era, from their perspective.' How can we visualize...oh! Ferb, I know what we're going to do today!"

Ferb nodded at him.

"Let's build a time-projector so we can look through time and do the research for our papers while still doing something cool today!"

Ferb stood up and headed for the parts bin.

"Hi, Phineas. Whatcha doin'?" asked a female voice from the gate.

Phineas looked up. Isabella had grown up and had filled out in very...distracting ways. Her magenta dress was awfully short, and clung to her curves; the white shirt under it kept it from clinging too much. He made sure his eyes jumped to her face, framed by long flowing black hair, and didn't linger on her chest too long; while she didn't get upset at him the way she did at Buford, he didn't want to encourage her too much. He liked her as a good friend, and knew she had had a massive crush on him for years, but he hadn't been ready to deal with a relationship when he realized, and there had been no way to tell her "not yet" that she wouldn't interpret as "go away". And he really didn't want her to go away.

"Hi, Isabella. We're getting ready to do the history paper with a time projector. Want to do yours too while we're at it?"

"Sure! Mind if the other Fireside Girls join in?" she asked.

"No, not at all. Hi, Baljeet!"

The Indian boy, still shorter than the rest, came in with his laptop. "Hello. What is it you are doing today?"

Isabella glared at Baljeet.

Phineas looked around. "Hey, where's Perry?"

Perry unlocked the door to the Doofenshmirtz Evil, Inc. penthouse and walked in.

"Just a minute, Perry the Platypus, I'll be right with you!"

Perry looked around. The usual -inator hiding under a sheet, several traps - he carefully stepped around a button on the floor - and the sound of flushing and hand-washing, followed by Dr. Doofenshmirtz coming out of a side room.

"Sorry about that, just awful timing."

Perry stepped forward, and metal arms snaked forward and grabbed his limbs. A fifth came from below to pin his tail.

"Ah-hah! Perry the Platypus, now I have you! And with my Time-Stop-Inator..."

He paused to pull the sheet off, revealing a complicated-looking gadget.

"...I will be able to stop time where ever I want! For, oh, about an hour at a time. Plenty to time for me to Take Over the Entire Tri-State Area!"

Isabella bided her time as Baljeet finished watching the view of Gupta Empire-era India through the time projector, and put his laptop away.

"Thank you very much, my friends. With these notes I will get an A+ on this paper for certain," he said.

"No problem, Baljeet," Phineas said. "Isabella, are you ready?"

Isabella stepped forward, smiling at Phineas. Tall and red-headed, with a noble nose and strong build, he was looking very nice in his usual striped shirt and shorts, and she needed to tell herself to focus on her task instead of him. "I'd like to see Danville, a hundred years ago."

Ferb, at the control panel, started tweaking the knobs. A view of old-time Danville appeared through the projector opening. Isabella opened her notebook and started taking notes.

Perry twisted, but could not get free from the metal arms. Doofenshmirtz, however, flinched at the movement and bumped into the control panel. A beam shot off out the window.

"Sorry, I'm just used to you getting loose all of a sudden and beating me up." He leaned out the window. "Sorry about that!"

He turned back, only to be hit in the face by a platypus-foot. "Ow! Yes, exactly like that! Hey, how did you get..." A platypus fist silenced him, and knocked him back into the control panel again. Another beam shot out, hit the mirror on the wall, and bounced back, stopping time for both evil scientist and platypus.

Isabella was almost done taking notes when the beam hit the time window.

"Whoa, where did that come from?" Phineas asked, jumping up to see what was going on.

Ferb shook his head as the control panel went wild.

The time-stop-inator beam was causing the time projector to flicker from time period to time period, flashing scenes from prehistoric times and just yesterday, all over the world. Isabella stood up and started backing away, but bumped into Phineas, who was moving forward. They fell over each other just as the projector's field expanded, pulling them in, before it vanished entirely. Ferb looked at the empty projector window, then down at the control panel. Smoke was starting to come from under the keys.

Isabella found Phineas on top of her, which was far from the worst thing that could happen from her perspective. He apologetically climbed off of her, and they looked around. This wasn't in Danville anymore, or anywhere she recognized; they were in a small clearing. The area was lightly forested and fairly flat, dusted by fallen leaves from the trees that were just starting to change color; the air smelled of pine and earth, and off to one side, she could hear a burbling stream. The temperature was a bit chillier than what they'd left, but not much. The sun was mid-way up the sky.

Phineas's voice was full of surprise. "What happened?"

"I don't know. Something hit the projector, we bumped into each other, and we ended up here."

"I bet it was another time-modifier beam of some sort. We could have ended up anywhen or anywhere!"

"Is there any way back?" she asked.

He looked around. "We don't look like we ended up in the recent enough past that there's a technology base we can work with. I think we need to hope Ferb is able to track us down. We probably don't want to go far from here."

"Why not?"

"If they had a fix on us when we dropped here, then they should be able to open a new portal... Any minute now... C'mon, Ferb..." Phineas paced around the clearing.

"But what if it takes him an hour to fix the machine?"

"Then they just open the portal to a minute or so after we got here; it's just time travel, it's not that difficult. We'll be back in time for dinner."

Baljeet looked at Ferb. "Where are they?"

"I don't know. More importantly, I don't know when they are either."