Draco smirked as he snuck into the Gryffindor common room. the blond hair forever being show up wanna be bad ass had searched high and low for the ULTIUMATE spell to use to not only get rid of the golden child himself, Harry potter, but would do so in the most degrading and humiliating fashion possible. 
even if he was caught after casting the spell, there would be nothing that could be done to undo it, it was one of the few unbreakable transformation curses out then and as such Harry potter would spend the rest of his life as a NAPPY of all things, the only question would be if he was a clean one if Draco was captured before he could wear him or if he'd be (as Draco would MUCH rather prefer) a shit swelled nappy, stuck tasting and smelling Draco's breakfast burrito for decades. 
Inside the common rooms and still unnoticed, he went on his way trying to find Harry. 

Harry meanwhile had been having a somewhat crappy week, and was looking forward to relaxing his favorite way which ironically, was wearing and filling a nappy while sucking his thumb and hugging a stuffie to his chest. 
Of course such a thing was a tad hard to hide due to the shared nature of the room though Neville and Ron who shared a room with him at the moment both knew and understood, with Ron all for it as long as Harry gave him a heads up first and sprayed afterwards and Neville clearly wanting to ask to be part of it (whether as a daddy or a fellow baby Harry wasn't sure) but hadn't managed to spill the beans yet. 
The was ONE slight problem though as Harry went and searched though all of his bags.. he was apparently out of nappies at the moment and hadn't noticed!
"No no no.. Come on I've had a week from fucking hell with Snape riding my ass so hard i think he's renting space in my small colon.. I CAN'T be out!" he groaned. 
As he tossed things out of the foot locker at the end of his bed Harry never noticed as Draco crept up behind him, coming out from under a cloak of invisibility with his wand ready, nor did he hear Draco softly muttering a spell and firing off a bolt of magic.
A bolt of magic that would miss harry as he drooped down to look under his bed last second and so not see the bolt bounce off of a mirror and come back hitting a wide eyed Draco.
The effects were instant, one second Draco had been standing there and the next there was a thick disposable nappy with a babyish print that hit the floor, all folded up and with strong tapes and slick plastic. 
 Poking his head up, Harry wrinkled his brow, then turned around and spotted the diaper on the floor by the cloak of invisibility and smirked. 
"heh, I guess Neville must of been hiding one?" he asked himself out loud, reaching down and scooping up the cloak and tossing it on Neville's bed and heading over to his own bed with the nappy in hand, glad he wouldn't have to wait till he could sneak away to buy more nappies.. never once guessing where the nappy had actually come from. 

Draco was screaming his head off even though he knew that there was no way anyone could hear him. Likewise, he was screaming for help even though he had picked this spell exactly for the fact there was no way out. 
the brat prince of Hogwarts had lost his entire future, a life full of women, boozing, being a elite and turning his nose up at muggles.. he'd be spending the rest of his miserable life filled with whatever Potter was about to fill him with and worse?
he'd done it to himself. 
'Maybe it's for the best no one CAN hear me or will know what happened to me.. Better daddy think I just vanished and died under Dumbledore's watch and at least get him kicked out and maybe arrested then him knowing..' Draco thought to himself, Picturing his father holding up a filled and taped up Draco with a finger and a thumb, holding his nose and giving him a look of disgust. 
'..Maybe this will be one of those spell where somehow I go all nappy brained and enjoy this.' Draco thought hopefully as he was unfolded, and got a glimpse of the golden child's rather rater member and smooth ass and pubic area.
'..is it wrong to wonder if he shaves because of the nappies or just hasn't..' Draco laughed bitterly, annoyed that someone who was clearly a nappy boy had such a big cock while Draco own was.. had been a mere 3 inches. 
'there's just NO justice in the world!' the nappy huffed as he was tugged up and tapped snug, his vision going dark though his sense of smell and taste got sharper and sadly confirmed what had been a rumor around campus:
Harry was a very poor wiper. 

Harry couldn't help but shiver with excitement as he tasted the nappy shut, Somehow THIS one felt more.. naughty then usual somehow even if he couldn't put his finger on WHY. 
'must just be from me thinking I was gonna have to potty like a stupid big boy.' Harry thought babyishly as he tented out the diaper, reached down and stroking himself though the diaper and suddenly at war with himself. 
with this CLEARLY the last nappy, he really should try and hold off filling it for a bit so he could crawl around but at the same time he wanted to make tinkles and stinkies and hump his stuffies. 
'who said being the golden child was easy.' he thought with a giggle, waddling over and wiggling his hips as he looked at his reflection, then frowned a little. 
This nappy was thicker then his normal ones and had some chibi designs on the front to go with the normal baby ones, of a blond little wizard. 
"huh. that almost looks like Draco." Harry mused out loud, tracing a finger over the front and then smirked. Of course if Draco WAS my nappy I'd show him NO mercy!" he laughed, shaking his head at the silly idea and having made his choice. 
what a silly thought that was, someone being turned into a nappy! Harry had seen a lot since coming to Hogwarts but he doubted there was a spell like that.
As he squatted down and started to bear down, letting out a series of farts that slowly got longer, stronger and wetter he banished the idea from his mind, it was time to do what he did best. 
Fill his nappies.

Draco was trying his best to zen out, to try and lose himself as quick as he could which wasn't as east as it sounds when Harry stroking himself in his nappy/Draco made it feel like he was making Draco deep throat him. 
'Great, my first blown job and not only am I the one giving it, I'm not even a fucking person during it.' Draco thought bitterly and then groaned as he felt Harry shift his weight and lightly rub the front of Draco, knowing what was about to come. 
'Ok here we go.,.. become one with the nappy.. go nappy brained!' Draco willed himself as the farts started.
Oh, to tell you that though a hidden miracle Draco found that Harry's farts smelled wonderful and he loved but this wasn't one of those stories, and instead Draco was mentally gagging, wishing he had A) hands and B) a nose he could cover with said hands as Harry blasted out gas that made Crab and goyle brush with spoiled oysters on the train car to Hogwarts seem like a fresh summers eve. 
'GOOD GOD MAN!! GO AND SEE MADAM POMFEY, AND HAVE HER TAKE WHATEVER SMALL RODENT CALLED UP YOUR ASS AND DIED OUT!' Draco mentally screamed and then started to sob as wet farts splashed him. 
'I'm having a nightmare. that's all, I'm having a nightmare and will wait up before Har-' Draco started, but before he could finish the thought Harry started to push out big thick log after big thick log into Draco, deforming his 'body while sadly leaving his mind in tract. 
And somehow smelling even worse.

In the next hour and a half that followed, harry filled his nappy two more times till it was sagging big time between his legs and naturally soaked it even more, marveling at how much this nappy was taking without leaking and deciding to stress test it by bouncing up and down on a hard wooden chair before enough was enough, He humped his nappy hard and hard and oddly had a mental image of Draco as he came HARD, too spent to change himself and drifting off to sleep with his thumb in his mouth and only being woken up hours later when Ron and Neville came in to ask him if he'd seen Draco, the brat had gone missing and for Ron to whine Harry was suppose to clean up after messing. 
Harry mumbled he hadn't seen Draco and said sorry to Ron, but was still too baby brained and sleepy to change himself and so Neville took care of it for Harry, letting the little guy conk back out and raising a eyebrow as Harry talked about the awesome nappy Neville had gotten him.

"Wait, you got him a nappy?" Ron asked, head out the window and sucking in the cold almost winter air. 
"no.. little guy must just be all out of it. I did pick him up a new pack while we were out today. Better pad him up since he's so out of it." 
"Grand.. just promise me your gonna get rid of THAT smelly thing!" Ron whined, pointing at the taped up and super wreaked nappy. 
"i think Harry has a diaper pail around here somewhere, But I don't know where.." Neville said, getting Harry in a clean nappy and tucked back into bed. "..think anyone would trace it back here if we just tossed it out the window?"
"I mean, I doubt anyone will care, it's just a shitty nappy." Ron said, stepping back from the window and taking out his wand and smirking. "but I'll give it a extra push! Pull!" 
And with that, Neville tossed the nappy up and Ron hit it with a push, sending it flying off into the woods.. never knowing that they had just tossed away Draco Malfoy.
And there was every chance given how much both hated him, they wouldn't of cared. 

The end