Mr and Mrs Dursley were happy to say that they were perfectly normal thank you very much. And as perfectly normal people they had a lot of pet peeves, for example they both hated traffic jams with passion. Mr Dursley especially was becoming increasingly agitated by the huge line of vehicles stretching miles ahead of his shiny company car. Dudley Dursley took after his parents in that respect and was in the process of venting his frustrations on the tiny boy sitting beside him as the car inched forward. Harry (the tiny boy himself) found that the traffic jam wasn't really that bad in comparison to Dudley's fists.
While he was pondering his relative's inexplicable hatred of, well pretty much everything, including unfortunately enough himself, he spotted a young woman frantically banging against the car doors and as she came closer he could hear her crying. Before Uncle Vernon could leap into another tirade against motorbikes (undoubtedly responsible for this travesty) Harry warily piped up
"Aunt Petunia, who's that lady?" Ignoring his uncle's rapidly purpling face was hard but Harry was nothing if not stubborn. "Aunt Petunia?" He prompted when she had yet to reply.
"What women?" Harry at four was smart enough to know that the tone of voice his aunt was using meant that he should just Let It Go but the lady sounded so scared and all the other people were ignoring her so he described her blonde hair and blue shirt and that he was very worried because she was bleeding from her head. But like the rest of the people in the cars, his relatives pretended that they couldn't see her even though she was right outside their car.
"But Aunt Petunia, she's right there - I think she's hurting!" He cried pointing to her terrified face peering into the windows. By this point Uncle Vernon was extremely angry his face had gone past purple and now looked rather white which to Harry was even more frightening. Turning in his seat he looked Harry right in the eye while Harry did his best to ignore the lady covered in blood pounding on the windows though he couldn't help glancing at her quickly every few seconds. Aunt Petunia was stiff and staring straight ahead completely ignoring the tension in the car.
"You will stop this nonsense right now boy or mark my words you will be in your cupboard till Christmas. You understand me?"
Harry made one last desperate glance to the window where the women still hadn't moved on from but before he could even think to speak his uncle spoke again and this time his voice was far more quiet but somehow sounded even more dangerous.
"I said do you understand me Boy?"
So he just nodded and looked down pretending not to see the lady like everyone else, tears sliding down his cheeks, and ignored Dudley's smug expression at Harry having gotten in trouble. The car remained quiet: Harry too scared to speak, Dudley content to poke at Harry, Aunt Petunia pretending nothing had happened and Vernon still livid, until when the sky had turned dark, they passed the reason for the congestion. There was a wreckage - a small red car crumpled up against a monstrous lorry. Blue lights lit up the carnage, broken glass glittered on the road; Vernon grumbled about his tires. It was then Harry saw her - the lady, she was limp and her head was smashed against the windshield of the little red car - there was dark liquid spattered everywhere and Harry just knew that it was blood - that she was dead. And it didn't make sense, because he could see her standing, yelling right outside the car, asking for help, she was alive he was sure. But not. She was in the car crash too. Harry didn't notice that he was crying and screaming and that Dudley (even though he couldn't really see the dead lady from his side of the car) followed his example and big fat crocodile tears were streaming down his face. He didn't see that Aunt Petunia was gently hushing Dudley or that Uncle Vernon was shaking in rage as Harry refused to shut up. All he could see was the lady, the one banging on his window and the one with her head smashed in the red car window.
Needless to say he was locked in the cupboard for a very long time. He never did forget about his first dead-alive lady, even though in the following years he saw many, many more even more terrifying ones he could still perfectly remember her blood-caked blonde hair and frantic wild eyes.