A new story for the new year. I've been wanting to write a next-generation Phineas and Ferb story for a while, but I had trouble coming up with a decent idea. I hope I don't disappoint. Enjoy.

Phineas and Ferb (c) Dan Povenmire and Jeff "Swampy" Marsh.

OC Next Generation Characters by me.

It was a historic day in Danville. As fate would have it this day would bring about the continuation of what was already an amazing legacy. There were two women, Vanessa Fletcher and Isabella Flynn in labour. The wives of the famous stepbrother duo, Phineas Flynn and Ferb Fletcher. It was a day that all of them would remember. For obvious reasons the women were in different rooms, and their husbands were right there with them. Phineas and Ferb had seen a lot of amazing things throughout their lives, but they would not miss this for the world. Vanessa Fletcher was having a particularly difficult time. She was normally a somewhat quiet woman, who only got noisy when it was time to sing a song, but even she could not help screaming in pain as her labour continued. Her only comfort during this time was her husband, holding her hand despite how tightly she was squeezing it. Isabella was not doing any better. She had never been so scared in her entire life. At the same time however, she was excited to meet her child and with her husband by her side, she knew she could get through this.

"Don't worry Mrs Fletcher we're almost there," said the doctor.

Vanessa was glad to hear this, because she would hopefully be holding her child in her arms soon. Unfortunately, her grief would be temporarily increased by the arrival of a certain relative. They could hear screaming outside the delivery room.

"What do you mean I'm not allowed in there? I'm that woman's father, making me the child's grandfather," said a voice Vanessa and Ferb immediately recognised.

"Oh no," said Ferb

A man suddenly burst through the doors. He was in his late fifties, hunched over and wearing a lab coat.

"Vanessa honey I made it!" said Heinz Doofenshmirtz, Vanessa's father.

The whole room was a little surprised by the sudden visitor.

"I'm sorry sir the pharmacy's down the hall," said one of the doctors, mistaking Heinz for a pharmacist like many others had in the past.

"Oh for pete's sake. I'm not a pharmacist, I'm Vanessa's father," said Heinz angrily.

Vanessa really was not in the mood to deal with her crazy father right now.

"Dad this is not a good time," said Vanessa.

"Oh, I know you're in pain, but it'll all be over soon. Let me tell you about your birth. Seriously your mother would not stop screaming throughout nearly the whole thing and she was in labour for nearly twelve straight hours. Honestly, I don't think I've ever heard a woman scream so much in my entire life, it's honestly amazing that she could even speak after the whole thing was over," said Heinz.

Heinz continued to talk about Vanessa's birth, which was only making the woman more stressed out.

"OH MY GOD WILL SOMEONE GET HIM OUT OF HERE," screamed Vanessa.

The doctors did as Vanessa wished.

"I'm sorry sir, but you're gonna have to leave," said one of the doctors.

"But I want to be here for the birth of my first grandchild," said Heinz sadly.

"Well, I'm sorry but she doesn't want you here. Don't make us call security," said the doctor.

"Alright, alright I'll leave, you don't have to be such a spoil sport," said Heinz.

As Heinz left, Vanessa's mother Charlene could be seen on the other side of the door.

"I'm sorry honey, I tried to stop him, but you know what you're father's like," said Charlene.

"MUM GET OUT," screamed Vanessa.

"Yes honey," said Charlene.

After the door closed Vanessa silently wished there would be no more interruptions.

"At least your parents respected our wishes," said Vanessa.

"Well, they're about to have two grandkids born on the exact same day, I have a feeling they didn't want to appear like they were picking favourites," said Ferb.

"I hope Isabella's doing better than I am," said Vanessa.

Unfortunately, this was not the case. In another room, Isabella Flynn was in just as much pain as Vanessa and was squeezing her husbands' hand more tightly. Thankfully, they had not had any unwanted interruptions.

"You're doing fine Mrs Flynn just keep breathing," said one of the doctors.

Isabella had been moved to tears by the pain and terror. But no matter how much pain she was in, or how scared she was, her husband was there and that was all the comfort she needed to get through this. Despite this, she needed to let her fears be known.

"Phineas, I'm scared," said Isabella, as tears ran down her face.

"I know. I am too, but I'm not gonna leave you. There is nothing that would stop me from being by your side today. I love you Isabella and I'm here for you," said Phineas.

In less than an hour both of them were ready to push. This created the biggest screams from both women. Eventually however, both children were born. Isabella was the first to give birth. Although the baby had to be taken away and cleaned, the doctor eventually returned with the baby wrapped in a blanket.

"Congratulations Mr and Mrs Flynn, it's a boy," said the Doctor, handing the baby to Isabella.

He was the most beautiful thing Isabella and Phineas had ever seen. He had red hair like Phineas, but his head was shaped more like Isabella's, but his nose was more triangular shaped, which matched Phineas' triangular head.

"Aww, I'm kind of sad we didn't get a Dorito," joked Phineas.

"Phineas, I love you, but I'm really not in the mood for jokes right now," said Isabella.

"So, what should we name him?" asked Phineas, looking at the child.

Phineas and Isabella looked at each other. No one could really explain how, but one look at each other and Isabella and Phineas immediately knew what they wanted to call their son.

"Sean," they said together.

Meanwhile, Vanessa had also given birth and she and Ferb were waiting for the doctors to return. Just like with the Flynn's, the doctor returned carrying the child in a blanket.

"Congratulations, it's a girl," said the doctor handing the baby to Vanessa.

Vanessa gave the biggest smile she had ever given when she held her daughter for the first time. Ferb was also smiling widely at the sight before him. Their little girl had green hair like her father, she also had his big eyes and square nose, but her face was more round like her mothers and the nose was a lot smaller. Ferb and Vanessa did not even need to ask the question, they simply looked at each other and knew what they wanted to name their child.

"Rosemary," they said together.

"Rose for short," said Ferb, as Vanessa smiled.

In the waiting room a total six grandparents were told the good news. Isabella's parents were allowed to go visit the Flynn grandchild first, while Charlene and Heinz went to visit their own. This left Linda and Lawrence outside, trying to decide which grandchild they should meet first. They didn't want to feel like they were picking favourites, especially considering Linda was Ferb's Stepmother, while Lawrence was Phineas' Stepfather.

"How about I go visit Phineas first and you go visit Ferb. Help show that a blood relation isn't the most important factor," said Lawrence.

"Sounds good to me," said Linda, and they went their separate ways.

Lawrence headed to Isabella's room and opened the door. Inside, he saw Isabella's mother, Vivian Garcia-Shapiro, holding her first grandchild.

"Oh Isa, he's so adorable," said Vivian lovingly.

It was then they noticed Lawrence was in the room.

"Hi Dad. Where's Mum?" asked Phineas, noticing Linda was not there.

"She's visiting Ferb, but don't worry she'll be here shortly," said Lawrence.

"Sounds good," said Phineas.

"So, did I hear correct? You had a son?" asked Lawrence.

"Yup, that's right. Dad I'd like you to meet Sean Flynn," said Phineas, gesturing to the child in Vivian's arms.

"Would you like to hold him Lawrence?" asked Vivian.

"Yes please," said Lawrence.

Vivian handed the child to Lawrence.

"We'll leave you three alone," said Vivian, and she got up and left with her husband.

Lawrence could not help but smile. This was now his fourth grandchild and he could not help but feel that every time another was born, the world became a better place to live.

"Phineas, you have no idea how great it feels to be a grandfather for a fourth time. However, some might argue I only have one grandchild," said Lawrence, remembering he was only Phineas' Stepfather.

"Don't start Dad. I don't care what people say. You are my father, meaning Sean is your grandson and I don't want you ever thinking otherwise," said Phineas.

"Alright," said Lawrence, who was happy to know that after all these years, Phineas still considered him his father.

Meanwhile, Linda went to go visit Ferb. She was unsurprised to see what was happening. Heinz was being a little too crazy with the newborn.

"Who's Grandpa's little scientist. You are, that's who," said Heinz.

Charlene took the baby off her ex-husband.

"Heinz, we said if you were gonna be too crazy you can't hold the baby," said Charlene.

"What, can't I be excited about my first grandchild?" asked Heinz a little upset.

"You can be excited Dad, but you have to keep it within reason," said Vanessa, who then noticed Linda. "Oh, hi Mrs Flynn."

"Vanessa for the hundredth time. Its Linda," said Linda walking in.

"Let's give them some privacy Heinz," said Charlene, handing the child to Ferb.

"But I want to stay with my grandchild," said Heinz sadly.

"Later," said Charlene, forcing her ex-husband out of the room.

Linda went and sat down next to her son and daughter-law.

"So, it's a girl right?" asked Linda.

"Yup, meet Rosemary Fletcher," said Vanessa, as Ferb handed his mother her granddaughter.

"Ferb, she's so beautiful," said Linda, as a tear ran down her check.

"Thank you mother," said Ferb.

After a while, Linda and Lawrence decided to switch places, so they could meet the other new grandchild. It did not matter how many new grandchildren they got, they were filled with joy each time a new one came along. Visitors kept coming throughout the day. Phineas and Ferb's older sister Candace and her husband Jeremy were overjoyed to finally have a niece and nephew, even though they already had three kids of her own. Their children, Amanda, Fred and Xavier were equally exited to meet their baby cousins. Childhood friends also came to visit. Baljeet and his wife Ginger were eager to meet Phineas and Ferb's new children, as were Buford and his wife Brigitte (who many were still amazed had agreed to move from France to America to be with Buford). Eventually however everyone had to leave, so the two mothers and their children could rest.

The next day, Isabella and Vanessa were sitting together in Isabella's room holding their children.

"It's still hard to believe they were born on the exact same day. Do you think Phineas and Ferb planned this?" asked Isabella.

"Knowing those two, I wouldn't be surprised," said Vanessa.

"Either way, I'm glad they share a birthday, it means we can celebrate them together every year," said Isabella happily.

"I look forward to it," said Vanessa.

At this moment, Isabella looked down at her son and then at her niece.

"Do you think these two will be friends?" asked Isabella.

"Of course, they're the children of Phineas and Ferb, I have a feeling that being friends will be in their genetic code," said Vannessa. "But if Phineas and Ferb have their way, I have a feeling they'll be best friends before they can even talk."

"Well Phineas already told me that he and Ferb have play dates planned," said Isabella.

"Yeah, Ferb told me the same thing," said Vannessa.

"Either way, we're family and that's what's most important," said Isabella.

"Agreed, I'm proud to call you and Phineas my in-laws," said Vanassa.

"As am I with you and Ferb," said Isabella. "Also, I don't think any can deny, that an amazing legacy has been continued today."

"That it has," said Vanessa.

Thanks for reading. This will hopefully be the first chapter of a series, if I can come up with enough ideas. Please let me know what you thought in the reviews, especially if you feel there are areas in need of improvement. More is hopefully to come.