Author's Note: I don't know when this takes place. Besides, this might not exist in my headcanon at all. Also, there will be a theory in this fanfic in which not everyone will comprehend. So, enjoy and give me some feedback as much as possible.

"That's weird." Mom said, "Lawrence, Candace has been acting weird since last night." They both look at Candace who is continuously playing with her toys instead of talking with her cellphone as usual. She was talking to them with more basic words, as she is about 10 years younger. Mom tried to approach Candace and tell her what they're going to do that day. "Candace, honey," Mom called. "We're going to the Milk factory tour today. And since you don't like milk, you-"

She got interrupted as her daughter hugged her tightly with tears, "MOMMY!" she cried. "I don't want you to leave me!" Mom sighed, hoping that this will soon be over, "You won't be alone." Mom replied. "Perry will accompany you. And if you want more company, just call your friends, but not too much. We don't want a party." Candace sniffled. "Perry?" she asked. Then came Perry being next to her, giving her a growl to mark his presence. Linda replied, "Yes, Perry's going to be with you. He's even with you right now." She pointed to the platypus as she said that to her. "OK..." Candace whimpered.

After that, downstairs, Mom, Dad, along with the little brothers Phineas and Ferb said their farewells to Candace. "Take care of house." Mom greeted. "I hope you'll have fun with Perry." Phineas greeted. They all left to the Milk Factory, leaving Candace being all lonely, with Perry of course. "Hey, where's Perry?" Candace asked. "Perry? Peeeryyyy!" As you probably know, Perry was hiding from Candace so he could do his secret agent work. He put on his fedora very quickly. After that he was reaching for a vase to access a tunnel to his lair and...

He got picked up by Candace while he was still wearing his fedora. "Oh, there you are, Perry!" Candace exclaimed. Worried that they will both be busted by the O.W.C.A., Perry turned off the watch which connects Perry with Major Monogram. "Perry?" Candace called. Perry replied with pet mode-like growl. "You... you have a fedora. Daddy likes to wear a fedora when he comes home." Perry was shocked after listening to what Candace said. Dad never wore a fedora when he comes home, maybe not at all. Unless...

Perry slipped out of Candace's arms and closed every door, every curtain, even every spy camera and microphone he had knew. After that he reached his fedora to get his translator he had build when he had free time from his work and pet mode time alone.

Perry took off his fedora as this even has nothing to do with his secret agent carreer. "Candace." Perry called her with his translator. "Perry! You can talk!" Candace exclaimed like what a kid would usually do when they see their pet talk. "I want to ask you something." Perry continued.

He brought her to the couch where the Flynn-Fletcher family usually had their conversations together. He turned on the lamp and started the talk. "Candace, how's your time with Daddy? Do you miss him so much?" Perry asked. Candace rubbed her head, "I miss him so much! I haven't seen him since last month. We had a nice time together, though he's sometimes scary when he's with Mommy."

Perry imagined how traumatic it is for Candace to come through all the harsh life experiences with her father... wait, last month? He knew that "Daddy" must be referring to her real father but last month? He figured out that either Dr. Doofenshmirtz used an inator against her, or that she suffers from severe amnesia. "I miss him so much that I hear Daddy's voice each time you talked."

Perry chuckled a bit. "Candace..." he spoke. "Let me tell you something."

Then comes a scene where a billboard with Ducky Momo accompanied with the words "I'm Your Best Friend" where the "Best Friend" was accompanied by a truck labled "Daddy is Day Special" with a flat tire. Another driver mentioned that it's "Father's Day", not "Daddy is Day". Then the truck driver said that he thought "'s" always results in "is".

Back to the Flynn-Fletcher household. We see Candace shocked, I mean real shocked. Perry expected her to be in doubt about him being Candace's real father, but it was actually the opposite. She actually hugged him like never before, even tighter then that time when Candace received the CD from the traffic cam. It had real warmth in it. She was really happy, no tears of course. "DADDY!" she cried. It was just as if her father came home from work. He remembered those days.

"Oh Candace, I miss you doing something like that to me." Perry smiled. "Aren't you confused why I look like this?" Perry showed his platypus body. "Silly Daddy! You're in a costume!" Candace giggled. Perry sighed in relief. "OK, Candace." Perry said. "Now that I'm here, let's have a little more time together."