Author's Note: Rated for child abuse, disturbing content, and character death (depending on how you read the end). Ignores post-book canon.
1. "Hey, Dudders!" Harry's smile shone bright as sunlight - almost as bright as the sparks dancing between his palms. "Look what I can do!"
Dudley's breath caught. For a moment, he remembered his parents warning him, in odd, hushed tones, to be on watch for anything - unnatural his cousin might do, anything - wrong about him. They always told him that, if anything like that happened, he should tell them at once.
If he'd been more cowardly, he would have recoiled, and maybe given Harry a warning. If he'd been smarter, he would have told him to keep a lid on it while the grown-ups were around. If he'd been wiser, he'd have taken Harry aside and told him about what his parents had said, and to do as he thought best with that knowledge.
But because, he was seven, and thoughtless, he only bent over Harry's hands and goggled. "Cool," he said. "How are you doing that?"
2. Dudley flinched and cowered back against the wood of the staircase. His mother was beside him, but right now the cold wall seemed more nurturing than her tight-lipped, unyielding form.
"And this - is for - trying - to taint - my son - with - your - unnaturalness - you - goddamn - FREAK!" his father yelled, punctuating each word with a blow from his belt across the back of Dudley's prone cousin.
He hadn't been so angry to start with- he'd just grabbed Harry and hit him across the face with his bare hand. But then there'd been a bang, and briefly Harry had been free of his father's grasp and running for his room, and his father had gotten mad.
"Stupid - unnatural - THING!" his father bellowed, hand swinging down to lash Harry again and again. "To Hell - with the day - we took you - IN!"
If Dudley had run towards him, and pleaded with him to stop - it wouldn't have helped, he accepted only years later. He might even have been disciplined himself. But it would have at least let Harry know there was someone who cared for him in that household, and maybe that would have made a difference.
But instead he huddled against the wall in terror, and wished he was anywhere else.
3. Dudley dared to look up from his toy trains only when he heard the now-familiar sound of the slamming cupboard door.
His parents had given all sorts of toys to "make up for having to put up with the freak". Trains, toy soldiers, teddies, puzzles, robots that lit up and made sounds and even moved if you wound them up first... Even Harry's old room.
He wanted his cousin back.
Taking a deep breath, he got to his feet and went to the door of his room. His mother was already there, as though she'd expected him. "I'm so sorry about the noise, Duddikins," she cooed, her sweet tones belying the hostility still evident in every line of her figure. It was all Dudley could do not to flinch. "It was just... that thing. The freak, I mean. He was causing trouble again."
"What did he do?" Dudley asked. He could still hear his father stomping downstairs and cursing. He tried not to make out the words. It was easier to ignore it if he couldn't understand it.
"It was horrible," his mother said, lowering her voice as though she were gossiping with the neighbors. "He was trying to call the police on us! Can you believe it? After all we've done for him!"
Dudley's gaze flickered in the direction of Harry's old bedroom - the one that now stood empty. His mother did not catch the movement.
"He was trying to get us in trouble," she snarled, all pretense of gentleness gone. "He wants us in jail, the horrible little thing! With common criminals! I know that's what he wants - that little ball of spite and malice - he said otherwise, but I know better - if Vernon hadn't caught him in time - oh, I'm so sorry, Duddikins, I shouldn't worry you with these things," she said, catching sight of his expression and shaking herself. She fished a sweet out of her apron pocket - it seemed she always had one, these days - and gave it to him.
Even if he didn't yet have the words for it, Dudley knew what his parents were doing was wrong. He knew, though he only knew it as an oily, oozing, wordless feeling that seeped between his shoulder-blades, that they had gone mad. He knew, although he did not know nearly how much so, that this madness could only end in horror.
And he knew, though he could not admit it to himself, that, if he wanted to stop it, he would wait until his parents were otherwise occupied, and call the police himself.
Instead, he stood mute and sucked numbly on his sweet, focusing on the burst of sugar as though it could block out the madman raving downstairs, the crying boy in the cupboard, and the odious woman before him.
"Give Mummy a hug," she said, stooping down to reach him, and he stiffly put his arms around her and let himself be swept up into her embrace. "I know what you need," she said, rocking him and patting him on the back like a baby. "This room isn't big enough for a big boy like you! I think I'll give you the freak's old room, too..."
4. It wasn't one big thing Dudley should have done; it was a lot of little things he could have done, and didn't.
He should have approached Harry quietly at school and let him know he'd stand by him. He should have crept up to his cupboard and shoved a sweet under the door - he had enough of them, these days. He should have let a teacher know what was going on - he couldn't see why they couldn't see, how they kept falling for the endlessly-rehearsed excuses about stairs and an ill-behaved, disobedient, and terribly clumsy child. He should have spoken to the cat lady next door, who had been looking strangely at them and at Harry more and more often in recent months. He should have done something, anything, to stop his parents. He should have-
But they had sat him down and talked to him quite earnestly about freakishness, and how it was corrupting, and how it could make anyone like freaks unless steps were taken to protect people against their true nature. His mother was particularly emphatic about that. That was why he'd heard them telling the neighbors they'd caught Harry stealing money from Vernon's wallet, when Harry had never stolen anything in his life. That was why they'd started making it known, in hushed tones, that Harry's father was a drunk and a criminal, and Harry's mother had taken drugs while pregnant with him. That was why it was essential for everyone to know Harry was a lying, cheating, violent, attention-seeking brat born wrong. Oh, perhaps he wasn't guilty of those crimes, but it was the closest decent, untainted folk could come to understanding his - unnaturalness. Only people like them, burdened with having to cope with such a creature, could understand.
He did understand, yes? He hadn't been tainted by the freak's - unnaturalness?
Long after, he would realize they meant that he might be bewitched.
At the time, however, he thought they meant that, if he showed the least bit of sympathy towards Harry, they would treat him as a freak too. He would be beaten, and stuffed in a cupboard, and blackballed to anyone who might have helped him get away - by his own parents. And without a shred of remorse.
So when he went white, swayed in his seat, and shook his head desperately, they took it that he had understood the gravity of the situation and smiled. And he, in his terror, saw their broad smiles and felt ice-water in his veins. He had to do whatever was necessary to keep them from deciding he was a freak too. Anything.
So he did.
And he would spend the rest of his life hating himself for it and wishing to God he could take it all back.
5. When Dudley woke up to a burning house, he wasn't even surprised.
He was surprised that other freaks showed up and got them out, then started asking what had happened to Harry. If they'd really been "watching" his family, where had they been before?
Where had they been when Harry finally broke, and sobbed out through his cupboard door a promise to Dudley's mother that he'd never be freakish again?
Where had they been when Harry spent the nights weeping in agony, and Dudley's father only banged on the cupboard door and screamed at him that he could give him something to cry about?
Where had they been when Harry was slurring and stumbling and could barely manage a few words at a time, much less a coherent sentence, and Dudley's mother had just said he was fooling around for attention?
Where had they been when Harry vomited fire onto the kitchen floor?
Where had they been after that? When Dudley's father had beaten Harry to make the little freak stop doing it, and beaten him harder when he couldn't? When they put out that Harry had gotten sick, stopped inviting neighbors, and slammed all the shutters? When Harry, blistered by flames from within and babbling at people who weren't there, could only sob that he was sorry, he was trying to hold it in, he was trying to make it stop, he wanted to be good, he wanted to be normal - he'd do anything, anything, if they'd never hurt him again?
When the cupboard's door exploded in a gout of golden flame and the cupboard's prisoner came prowling out on all fours, all humanity gone from its snarling, half-melted face?
When Harry's old bedroom was converted into an emergency holding cell, and Dudley's father appeared at work after a week's absence, covered with self-treated burns and muttering about a terrible fireplace accident? When the frantic debates went on all night, barely audible over the screaming, as to whether they dared kill the freak - if his kind would find out? When Dudley stood before the door to his cousin's old room, tears running down his face, and choked out apologies to something he wasn't sure could still understand him?
Now they chose to come for Harry?
He should have asked, but he never did. Not when the old man forced the truth out of his parents, not when he swore them to secrecy, not when he fed them the official story that it had been a terrorist attack, not when he put them in "protective custody" for life, not when he held a press conference for the "grieving Muggle relatives" - never. Dudley kept his mouth shut and his head down, guilt gnawing at his guts, and suppressed the urge to vomit whenever the most unnatural people in the world reassured each other that, really, it was probably somehow the freak's own fault anyway.
Wherever the thing that had once been his cousin had gone - he hoped it was better than home.