Not the life he thought.
A/N: Got this idea from reading something on Pottermore (won't specify what in case you haven't unlocked it yourself) hope you enjoy.
It was his first year. Everyone was excited. They had his books and a wand that seemed a little temperamental but but he'd train it. Everything was packed and on the train.
In the back of Harry's mind, he tried to recall receiving the letter with green ink. He couldn't remember ever seeing it. They'd had to borrow the book list from one of his cousins because they couldn't find it. And come to think of it he'd never exactly seemed to show signs of being magic, not like some of his older cousins. But no matter, he was on the train now and it would all work out.
When they got to school, Hagrid led them to the boats and Professor McGonagall mete them at the doors to the Great Hall like she always did. It seemed to take forever but finally the class list got to P.
"Potter, James Sirius." came the voice of Professor McGonagall. James hurried forward eagerly. He scrambled up onto the stool as Professor McGonagall placed the Sorting Hat on his head. It took a moment to think before commenting:
"I'm sorry but there's no wizard here."
There was a stunned silence before James jumped off the stool and ran from the hall.
When Harry got the news that James was a squib, it sadly confirmed something he'd suspected but tried to ignore while on the train platform 9¾. He felt sad for James as he knew how much James had been longing to finally go to Hogwarts with his cousins.
James ended up going to a Muggle school. While his cousins and siblings tried not to talk about school, as they knew it upset him, James grew bitter about being a squib.
In his 16th year he ran away from home. Ginny was beside herself. Nothing Harry could say would ease the pain.
Harry went up to London to try and bring James home. But James, who was staying at the Leaky Cauldron, refused to see him. He told Harry that he had disgraced the family name and his namesakes and would never be able to return home. When Harry tried to tell him about how much his mother missed him, James exploded.
"It's too painful. Seeing everyone enjoying being magical and knowing that I will never have that. I'm sorry but I can't come home."
Harry tried to keep in contact with James over the years but James never replied to his letters.
A few years later, Albus came home with a Muggle newspaper with James' picture on the front page. He had recently married the daughter of a Duke and had neglected to invite his own family. Harry was hurt but sent a letter, by Muggle post of course, wishing the best of luck in their lives.
A few more years past and Harry received a letter by Muggle post informing him that James and his wife were expecting a child and that they would love for Harry and the family to be there for the birth.
Harry, Ginny and the kids caught the train to London. They met his wife Eleanor for the first time. She was almost 9 months pregnant. They were surprised at the birth to learn it was boy/girl twins! James and Eleanor agreed to name them Lily and Arthur after each of James' grandparents.
Eleven years later, James came home from work one day, just days before the twins' eleventh birthday, to find Professor Neville Longbottom in the living room. Neville had been named Headmaster after Professor McGonagall had retired. The twins, it turned out, were eligible to go to Hogwarts. While James initially wanted to say no, the image of his daughter on her knees in front of him, tears in her eyes, begging to be allowed to go changed his mind.