Epilogus iugis is a connected set of short pieces.

I'm using purely book canon. JK Rowling did write an article later on that makes my universe AU if you count it as canon. I don't, so my Percy's wife is not her Percy's wife etc.
Oh I could be said to break book canon in one way. Harry tells Albus that the hat will take your wishes into consideration and put you where you want to be… but, of course, he's only saying what he thinks happens from his own experiences. Or maybe I just think the hat knows more than you might be saying about what are your true wishes.

Rose is the daughter of Ron Weasley and Hermione Granger. She is a first year.
Albus is the second son of Harry and Ginny Weasley. He is a first year.
Scorpius is Draco Malfoy's son. He is a first year.
James is Harry and Ginny's first son. He is a second year and in Gryffindor.
That's all canon – it's in epilogue of HP and the Deathly Hallows. Percy is also shown to be on Platform 9 ¾.
Frederick is the son of Percy Weasley. He is a second year.
He and his mother are purely my invention.

"And, Frederick?"

"Yes, Father?"

"This term try not to…" Percy's voice trailed away. Try not to what? He looked at his son. Red hair smoothed into a neat cap, Gryffindor tie beautifully tied, robes precisely the right length Frederick looked back. His trunk Percy knew was just as beautifully neat and every set book was already read and several neatly rolled scrolls of notes filled the till of the trunk. At his feet a cage contained his rat Harvey (I don't need an owl, Father – they're too expensive. The school owls are always available for letters.). Harvey cleaned his whiskers once again, blinked sleepily at Percy and curled back up – neatly – to go to sleep. Try not to be so perfect?

Percy shuffled his feet under his son's endlessly patient look. Gratefully he turned to Edmund Ironsides – thumping old bore that he was – when he hailed him with a question about broomstick regulations.

The train began to huff and puff as it gathered steam to depart. Percy broke an awkward silence.

"You'd better hurry on – wouldn't want you to miss the train."

Frederick blinked a little owlishly. "No, Father." He looked down at his feet.

Percy wished, not for the first time, that there were text books for sons. He could study, he could learn – he'd always been good at that.

"Your mother... I'm sure your mother will send an owl. She would have loved to have been here but, you know, this conference on Ancient Runes in Romanian Vampire Literature, well, it's important…" he trailed off as Frederick lifted his head and looked at him.

"No, she wouldn't," Frederick said softly.

Doors were slamming along the train as they looked at each other. Percy knew, uncomfortably, that there was nothing else to say. Frederick had never been a child you could lie to. Wordlessly he held out a large bar of Honeydukes chocolate. Frederick took it with a nod. Percy cleared his throat as a guard fussily approached.

"Remember to eat some Toothflossing Stringmints afterwards."

Frederick nodded – then suddenly hugged his father hard. A whistle sounded and Frederick tilted his head back and looked up at his father. "It's a short term," he said urgently. "I'll be back soon."

He stepped back and with almost matching gestures father and son straightened their robes. Percy waved as his son climbed on to the train. Frederick let himself look back once.