Oh, if everything was different. If they have lived.
Uncle Remus and Sirius, also know as the-best-godfather-ever, would always be around. Making jokes, telling stories, babysitting whenever James and Lily needed a night out.
Lily would always read bedtime stories for Harry, muggle ones and wizard ones. She say that her boy would have the best of both worlds. And James... God, he love his family so freaking much. He's constantly making stupid faces for Harry to laugh, making his patronus run around the living room. And the little boy giggles.
Harry grow up so loved, with everything he might want, but do not turn into a spoiled kid. When he's about 4, his parents takes him to his first day at school, a muggle school. He is a chatty boy, and the teachers are delighted with this lovely kid. When James and Lily go pick him up, all the parents are surprised because they are so young. Harry run into them, and jumps on his father lap, telling them how much he enjoyed the classes and all about his new friends.
His childhood is having his friends at home, his parents cooking brownies, Sirius and Remus showing up and joining them on hide-and-seek. Is going with James and his godfather to quidditch games, opening a large package on his 6th birthday with his first real broom in it. Is spending hours with his mom in bookshops and video rentals, leaving with several books and movie tapes. Is falling asleep on sofa with his parents watching Star Wars every Friday. Is complaining about his eyesight, then going to choose glasses, and James saying that "the round ones are really cool, you will look like John Lennon, son!" Is being told about Hogwarts his whole life, and dreaming with the day that is going to be his turn. Is getting his letter and everybody is crying so much and Harry is so bloody happy that day finally come. Is going to Diagon Alley on his birthday with his family. His parents give him a Nimbus 2000, Uncle Remus and Sirius give him this beautiful white owl, named Hedwig. They all buy his school stuff and have giant sundaes on Florean Fortescue's Ice Cream Parlour.
On September 1st, the 5 of them are at Platform 9 and 3/4. Harry is jumping with excitement and accidentally steps on a red head boy' foot. He's George Weasley, and his family know Harry's. They hug, and the boy's mum introduce her sons and daughter, an army of red heads. Percy, Fred, George, Ron and Ginny. 10:57 and James refuses to let his son go. Hugging him tight, he ask him to write every single day. Harry smile, hugging his father back and promises he will. Lily straight his glasses and kiss his forehead, telling him to learn a lot and make friends. Sirius messes his hair, Remus put and arm on his shoulders and both whisper him to have fun and find a little trouble. He smiles with that mischievous look that he learned from them. Harry wave to them as the train leaves, screaming goodbye and smiling wildly.
When his first letter came, James and Lily couldn't be happier that their boy are at Gryffindor and is already so adapted to Hogwarts life. As he promised, a new letter came everyday. And one day, two letters came. One from Minerva and another from Harry, saying that he's the new seeker. James goes around the house with the biggest smile, screaming because "LIL OUR SON IS THE YOUNGEST QUIDDITCH PLAYER IN ABOUT A CENTURY" and "I KNOW JAMES, SIRIUS AND REMUS ARE GOING TO FREAK OUT". The next day, in Hogwarts, Harry receives a Howler and gets a little worried, have he done something wrong? He opens and his mum and dad are speaking at the same time, Sirius and Remus on the background, the four of them so clearly happy that all the students laugh, and Harry is amazed by his family.
Back home at Christmas, he brings the Weasleys with him. Fred and George tell the Marauders all about their pranks and show them the map they stole from Filtch. James and Remus laugh at their faces while Sirius tell them who Moony, Padfoot and Prongs are. Percy ask Lily for advice, how being head girl was like. She's happy to tell him everything about it and also tell not to worry so much. Harry and Ron fly around the house, eat until almost throw up, and have a wonderful Christmas. They all go back to school with candies and chocolates and a lot of stories.
To this day, on every vacation or holiday, they divided their time between the Burrow and the Potter's. James, Lily, Sirius and Remus always go have dinner with the Weasley's while his kid are with them, so does Molly and Arthur. Hermione, of course, is always with them. She and Ginny spend hours talking to Lily about school, boys and everything. In the summer of their third year, Remus suddenly jumps on a chair, announcing that he is the brand new DADA teacher and they all go wild. Harry and Ron almost can´t control their excitement, saying how cool is going to be. James, Sirius and Lily, knowing the struggle to get a job because of his "furry problem", are so happy he achieved it that barely can stop laughing.
And so the years pass by. James and Lily continue to receive strange looks for being just 37 and having a 17 years old son. Remus is one of the best teachers, and almost every single student loves him. Sirius still works at the Ministry, as an auror. Lily works at St Mungus and James is starting to think about leaving the his successful career on Quidditch to join Sirius.
On their graduation day at Hogwarts, Harry, Ron and Hermione have the biggest family. They almost couldn't take a photo with all of them in it, so everyone cheers when they all fit. Suddenly, Harry is so sad to leave the castle, his second home, but then look at his parents, James kissing Lily in the forehead as she laughs at something he said. He join them for a family hug, whispering that he love them, and couldn't help but feeling so blessed at that moment.