A/N: This is a random idea me and my neighbor thought of! Phizzabella (PhineasxIsabella) Enjoy!
Disclaimer: I do not own Phineas and Ferb or any of the characters.
It was a beautiful sunny day in Danville, and stepbrothers, Phineas and Ferb, were lounging under the large tree in their backyard. Phineas sighed, "What to do on such a beautiful day?" he asked dreamily. Their pet platypus, Perry, made his signature platypus clicking sound.
"Hey, Phineas, whatcha doooooooin?" asked Isabella, gazing at Phineas lovingly.
"We don't know yet," replied Phineas matter-of-factly.
"Well, I just got a hamster and he has this cute little ball thing look," she told them excitedly, pulling out a small furry animal in a hamster ball.
"That's it!" exclaimed Phineas, standing up and looking determined. "We will make the biggest human hamster ball of all time!" Isabella smiled,
"Wow! That sounds like fun, can I help?" she asked sweetly.
"Uh…sure," Phineas's heart beat a little faster and his stomach got a strange, tingly feeling when he caught sight of Isabella. I feel weird, he thought dizzily. "Guys, I don't feel so great," he commented.
"Aw, why don't we go inside and tell your mom," suggested Isabella. Phineas and Ferb both nodded at the same time, and the three of them walked inside.
"Mom, I feel weird," Phineas complained when they saw their mom.
"What's wrong honey?" she asked with a concerned, motherly look on her face.
"My stomach feels all tingly," he explained.
"Mrs. Fletcher," interrupted Isabella, "The Fireside Girls and I still need our health care badges, so maybe we could find out what's wrong."
"I think that's a great idea," replied Mrs. Fletcher.
"Great, I'll go get them," she said, and hurried out the door, beaming. Phineas suddenly felt normal again as she ran out of sight.
"Wait, I feel normal again," Phineas told them with in an amazed tone, but as Isabella trotted back into the room, he had that tingly feeling again. "Never mind," he groaned with a sigh, and Isabella ran off again. He instantly felt better again once she'd left. "Wait, it's gone again," he called after her again, but when her face reappeared, the strange sensation came back. "It's back." At that moment, everything came into perspective for Isabella, though she didn't know the real reason why she was the cause of it, she knew she was responsible for Phineas's "sickness". She put her head in her hands and started crying uncontrollably.
"Isabella, what's wrong?" asked Phineas worriedly.
"Phineas, I… I think it's me," Isabella chocked out between sobs.
"You think what's you?" he asked, cocking his head like a curious puppy.
"Y…your s…sickness. It's my fault!" she cried.
"What? How?" asked Phineas.
"I… I don't know why, but every time I come into the room, you feel bad again, and every time I leave, you're fine again!" She sounded as though she were sick herself as she explained it to them between miserable sniffles. Just then, Phineas's sister Candace walked in and took in their faces. Phineas and Ferb shared a surprised and slightly worried expression, and Isabella's face was hiding in her hands, her shoulders shaking as she slowly slid to the floor and dug her distressed face into her knees and wailed pitifully.
"What is going on here?!" shrieked Candace, causing Isabella to look up with her watery eyes, her sweet face streaked with hopeless tears.
"I…I think Phineas is allergic to me," answered a heart broken Isabella.
"WHAT?! Why do you think that?" asked Candace.
"Well, I get this weird tingly feeling in the pit of my stomach…and my face starts to get all hot… and my heart pumps really fast like I just ran for a really long time every time I see her, and when she leaves, the feeling goes away, so we figured…." Phineas started to explain, but saw the look on Candace's face before she started laughing hysterically.
"This isn't funny Candace!" yelled Isabella defensively.
"You're ha not ha allergic ha to ha Isabella!" exclaimed Candace sincerely, though she was still laughing.
"Then what is it!" they exclaimed.
"Phineas," Candace beamed, "You're in love!" she exclaimed.
"WHAT?!" he screamed. This definitely was not what he was expecting her to say.
"It's all the symptoms of love sickness. I would know, I've had it!" Candace insisted. Isabella stopped crying and looked back and forth between giggling Candace and surprised Phineas. Then suddenly, Isabella broke out into a fit of hysterical laughter.
"Why are you laughing?" Phineas asked Isabella.
"I was so worried all this time that you wouldn't like me anymore 'cause I made you feel funny, but instead, it was the exact opposite!" she managed to say between giggles. Then they all laughed, and eventually, Phineas and Isabella rode off into the sunset on a white stallion. Okay, maybe not a white stallion, but they held hands and walked into the sunset.