A look at one of the ways Harry's rejection by Cho could have gone after p.397 of GoF.

Instead of going back to the Common Room in failure, he decides to ask the first woman he meets.
The next woman he sees is having a row with her date for the Yule Ball: Pansy Parkinson.
This is my best estimation of a gradually more mature story. Elaboration on magic, relationships, other cultures and traditions and, of course, the fallout from Harry Potter - the Boy-Who-Won, Tri-Wizard Champion, seeker and heir to a great house - getting to know a girl from a very different world to any he has encountered before.

They stood there looking at each other, and then Cho said, "Well —"

"Yeah," said Harry.

"Well, 'bye," said Cho, still very red. She walked away.

Harry called after her, before he could stop himself. "Who're you going with?"

"Oh — Cedric," she said. "Cedric Diggory."

"Oh right," said Harry.

His insides had come back again. It felt as though they had been filled with lead in their absence.

Completely forgetting about dinner, he walked slowly back up to Gryffindor Tower, Cho's voice echoing in his ears with every step he took. "Cedric — Cedric Diggory." He had been starting to quite like Cedric — prepared to overlook the fact that he had once beaten him at Quidditch, and was handsome, and popular, and nearly everyone's favourite champion. Now he suddenly realised that Cedric was in fact a useless pretty boy who didn't have enough brains to fill an eggcup.

"Fairy lights," he said dully to the Fat Lady — the password had been changed the previous day.

"Yes, indeed, dear!" she trilled, straightening her new tinsel headband as she swung forward to admit him.

Inside was full of music, chatter and gossip and he realised he couldn't bear the idea of having to confess that he had failed. Part of it was pride – he was a Tri-Wizard Champion, after all. But another part of it was that he just didn't want to see Hermione's smug told-you-so smile.

"Sorry," he said to the Fat Lady, "I just remembered there's something I have to do."

He wasn't going to go back until he had a date for the ball, even if it took him all night.

The Fat Lady harumphed her displeasure and swung shut again as he turned and walked back down the corridor to the school proper, pondering his options.

He made his way down to the great hall and sat at one of the benches for a while, pondering what he was to do next. At one point he saw an attractive Gryffindor girl walk past him, gossiping with her friend. He vaguely recognised her as being in Ginny's year, but her name escaped him. He stood, grabbed by a moment of madness and walked quickly to catch up, but veered away as he lost his nerve before she noticed him.

This is ridiculous, he thought, thinking again about the absurdity of how much easier it was to go into an arena with a dragon than talk to a girl.

Walking up the nearest staircase, he ducked into a bathroom and splashed some water on his face. He waited to make sure that he was alone and rested his hands on the side of the cold porcelain of one of the hand basins, staring at himself in the mirror.

"Right, you bloody coward." He said, trying for his best what would Sirius say tone and bearing, which actually helped him make a decision. "You're going to have a piss, wash your hands then head out there and ask the first girl you see – between third and… sixth year – to go to the ball with you, right?"

His reflection nodded, his mouth set in a hard line.

Swallowing hard, he realised he did have to pee.

He emerged from the bathroom a minute later with a half-crazed, steely determination. The corridor was, predictably empty.

"Typical." He said to himself.

Looking both ways down the corridor, he chose to go right at random and after a few turns, climbing another staircase and a random left, he heard raised voices.

"… matters because what I think should matter to you, you can't just make choices on my behalf." Said a strong girls voice, slightly shrill with emotion and definitely familiar, but distorted by the stone walls.

The sounds of footsteps were growing closer.

"Are you serious?" came the voice that could only belong Draco Malfoy.

Harry rounded a corner and saw Malfoy was talking to Pansy Parkinson. He looked sheepish and embarrassed while she looked furious.

"Yes I'm serious, you… conceited arsehole!" She shrieked, pushing him and storming off in the direction of Harry.

Oh bloody hell, what've I walked in on here? Harry thought, considering turning away for a moment.

Malfoy looked up and their eyes met. Harry saw him mouth something obscene and rub his face. Harry felt a moment of empathy for Malfoy, but buried it deep with surprising ease.

"Pansy, please." Malfoy said, sounding exasperated.

Harry, who had never exchanged more than a dozen words with Pansy Parkinson, now took a moment to really look at her. She had a high face, fine and pretty, with faintly tanned skin and a piercing blue eyes, all of which were emphasised by her chin-length black hair.

She stopped and took a deep breath, met Harry's eyes and scowled at him, then turned on her heel. "Pansy, please what?"

Draco looked momentarily stricken. "Let's go back downstairs, you don't have to wear them – I really mean it. I didn't mean to presume."

"I know you didn't mean to, Draco. But that's kind of typical, isn't it? You don't mean to, but you presume because you don't think."

Harry, suck between having to turn away or continue down the corridor and walk past the pair, opted for the latter, stepping onward a few steps behind Pansy.

"You were so enthusiastic, I thought – ", Draco started.

"Thought what?"

Harry passed Draco – a few more steps and he'd be away – but noticed as he rolled his eyes.

"And now you roll your bloody eyes at me!?" Pansy roared.

Draco, bewildered, raised his hands in a placating gesture.

"How about you, Potter?" She said, totally unexpectedly.

Harry stopped dead and turned around.

"What?" He and Draco said together.

"Would you presume to just buy your date dress robes without asking her first, then throw a hissy-fit when you – quite reasonably – explain for the hundredth time that you hate pink?" Pansy was flushed, breathing hard, her eyes blazing. She looked like she was holding back tears of frustration.

"Umm…" Harry said.

"Oh, grow up Pansy. Now is not the time to be airing our dirty laundry, especially around Saint Potter." Draco scoffed, clearly biting back anger now.

Harry sucked in a breath through his teeth – that was about the worst thing Draco could have done. "I… I don't – " He started.

But Pansy was fit to blow. "Grow. Up? You conceited wanker, Draco! I was really looking forward to going to the ball with you, but now… God, if it wasn't so late to get someone else!" She cried out in frustration and anger and stormed forward, heading between Harry and Draco.

"I will not go with someone out of obligation!" Draco shouted, firing up himself for the first time.

Then Harry found himself speaking automatically: his lips moving seemingly of their own volition. "Why don't you go with me then?" He asked.

The silence in the corridor was suddenly deafening.

Draco made a double-take between Harry and Pansy. "What?"

Pansy looked at Harry, silent for a few seconds, looking like she was taking him apart, appraising him with her eyes for the first time.

"If you want, of course. You can wear whatever colour dress robes you want." Harry said, shrugging in what he hoped was a 'if you fancy' kind of way.

"Are you taking the piss, Potter?" Draco asked, looking astonished.

Pansy smiled a simultaneously furious, but radiantly pretty smile. "Well yes, why not Potter. Come find me after dinner and we can discuss what I will wear."

Harry's stomach clenched with disbelief. Like his relationship, such as it was, with Draco wasn't bad enough. What was everyone in the common room going to say about this?

Pansy was walking toward him, stopping with less than a foot between them. She smelled like peppermint and some kind of perfume. She scrutinised him for what felt like an hour, but couldn't have been more than a second before Draco chimed in.

"Pansy, come on. That's more than enough."

"Get fucked Draco. Ask Crabbe or Goyle to go with you, or that Gryffindor girl you're always mooning after if you want. I'm going with Harry here." She said, looking back at Draco who had bright red patches on his pale cheeks.

She turned back to Harry and smiled. It completely transformed her face from her usual pugnacious sneer into an expression that could really be called beautiful. "After dinner?" She asked.

Harry smiled back, unable to help himself. "After dinner."

She touched his cheek gently and flicked – a little irritably – at his messy hair. "What an interesting idea." She said, before leaning in closer, so close he could feel the heat of her next to him. "We will cause a stir."

Then she was off, her short heels clicking on the stone floor and Harry was left alone in the corridor with Draco, fifteen feet between them.

"You know, Potter…" Draco started, "you're a real pain in my arse. Good luck." He said, rolling his eyes and walking past him in the same direction Pansy had gone.

Harry blew out a long breath. She was right of course: they were going to cause quite the stir.