Hugo could never be their favorite child.
See, it wasn't because there was anything wrong with him. Far from it. Or even anything particularly different between him and his sister. Not exactly.
He had the Weasley red hair, but his mother's freckles and dark eyes and curls – just as Rose had.
He was in Gryffindor – just like Rose.
He played Quidditch – just like Rose.
He loved to read, and play pranks, and make friends, and do magic – just like Rose.
They were really remarkably similar.
Hugo remembered, on the day Rose got on the train for Hogwarts for the first time, how their father called out to his daughter, "If you're not in Gryffindor, we'll disinherit you." His father's voice still rang out in his ears so clearly. He had been a little serious, no matter how much their mother had tried to convince him otherwise.
And so, when the sorting hat was placed on Hugo's head two years later, he screamed so loudly in his head that the Hat was forced to place him nowhere but in Gryffindor. He and his sister even had that in common - he was convinced she had done the same, even if she insisted she hadn't.
"You do belong in Gryffindor, Hugo," Rose told him once, after the first time points were taken from Gryffindor on his behalf, "The sorting hat has never been wrong. Never."
"And who told you that?" He said in a small voice.
"Harry did."
Hugo never did know it for sure, but Rose had the same feelings about being in Gryffindor. She didn't think she belonged either.
Hugo and Rose always got along quite well.
It wasn't always obvious that Rose was the favorite child. Actually, they, each year, had semi-comedic display of deciding who the favorite child was between the two of them.
It was hardly a competition the years Hugo won.
Like the year he sent an owl nearly every week telling his parents how much he hated not being able to read well or look at things closely without getting a headache, and how he probably needed glasses, but his parents never told him what to do about it (they felt awful once they found out how terrible his vision actually was).
Or the year he caught Dragon Pox from Lily and ended up in St. Mungo's with the worst case the Healers had ever seen in a boy his age (they had forgotten that it was Rose who had already had it as a small child, not Hugo, and hadn't give him any potions to make him less vulnerable).
It was Rose the year Hugo had nearly killed her with a few wrong ingredients in the Calming Draught that was supposed to relieve her anxiety before an exam (the matron in the hospital wing was furious. "You substituted mooncalf dung with a chocolate frog?").
Hugo the year Hermione had somehow managed to make the child's left arm disappear while cooking breakfast.
Rose the year their father had both splinched her in the singular time he took a child apparating with him and forgotten how to reverse the damage (their mother was livid. "What in the name of Merin's pants were you thinking, Ronald Weasley? Endangering our child by your utter incompetence?")
And so on. Each of them had always their fair shot of winning.
Hugo barely remembered the day that it happened.
It was the middle of a Quidditch practice. Hugo was a Keeper – just like his father. It was pretty impressive, if he did say so himself, for a third year. And Rose was a chaser. The best one.
It was mostly a blur.
Rose had the quaffle and then she didn't. Rose was in the air and then she wasn't. Hugo couldn't explain what made her fall, all he knew is that she was on her broom and then she was plummeting towards the ground of the pitch. It was ineffable.
It was just a practice. No one was there watching. No one had their wands on them.
Aresto Momentum. Hugo knew the spell and at once pointed his hand at her and screamed it with all the might that he could muster. But he did not have his wand, and he was too young and not powerful enough to do his magic without his wand. It did nothing but make his arm feel tingly and his body feel tired. It was of no use.
All he remembered afterward was falling to the ground himself, although not hard, and it did not hurt. All he knew is that he was on the ground.
And there was screaming, some of it came from the Quidditch captain – James – who was screaming and yelling for someone to get help and to get the headmaster and to get anyone to just help. Some of it, he realized a bit later, came from his own mouth.
And they tried to save her, but it was too late.
It wasn't until after that Hugo began to realize the shift in his parents' views of the "favorite child."
"You loved Rose more!" He shouted once in a fit of rage, his eyes busting with tears, at his mother and father, when they requested that he quit Quidditch.
"No," his mother said, grabbing the boy's shoulders in her hands, "We love you more because of Rose."
A moment later, when Hermione had stood up to face her husband and the child had stormed away angrily, she whispered to him, "Maybe we should just let him play, make him happy."
Ron shook his head, his own eyes as teary as his son's, "I'm not going to lose both of them, Hermione. We can't lose both of them."
The thing is, Rose was not anymore perfect than Hugo. But now she was. She didn't have a chance to grow up and let them down.
How Hugo was supposed to live up to that, he had no idea.