I give the credit to part of this chapter to J.K. Rowling, as I used quotes from the seventh book.
Suddenly me, Ron, Hermione, and Ginny fell into a different world, a world I had already visited. Hermione fell onto the ground, and Ron in a pond. "Bloody hell..." he murmured. I had landed by Hermione, and Ginny fell into a tree, tangled up in its twisted branches. "Diffindo," I said, and the branches broke off, freeing Ginny. She came over to me, as did Ron and Hermione, and we watched a boy with overlong black hair and mismatched clothes, who looked to be no more than 9 or 10 years old. It was Snape. I, of course, had already experienced the dying headmaster's memories, but everyone was intent. My gaze flicked to the 2 young girls swinging. "Lily, don't do it!" shrieked the elder of the two. But the girl, Lily, had already let go of the swing at the very height of its arc and flown into the air, quite literally flown, launched herself skyward with a great shout of laughter, and instead of crumpling on the playground asphalt, she soared like a trapeze artist through the air, staying up far too long, landing far too lightly. "So that's your mom," Ginny smiled.
"Mummy told you not to!"
Petunia stopped her swing by dragging the heels of her sandals on the ground, making a crunching, grinding sound, then leapt up, hands on hips.
"Mummy said you weren't allowed Lily!"
"But I'm fine," said Lily, still giggling. "Tuney, look at this. Watch what I can do."
Petunia glanced around. The playground was deserted apart from themselves, and though the girls did not know it, Snape. There were also four time traveling teenagers watching the events of the day that was so long ago. Lily had picked up a fallen flower from the bush behind which Snape lurked. Petunia advanced, evidently torn between curiosity and disapproval. Lily waited until Petunia was near enough to have a clear view, then held out her palm. The flower sat there, opening and closing its petals, like some bizarre, many-lipped oyster.
"Stop it!" shrieked Petunia.
"It's not hurting you," said Lily, but she closed her hand on the blossom and threw it back to the ground.
"It's not right," said Petunia, but her eyes had followed the flower's flight to the ground and lingered upon it. "How do you do it?" she added, and there was definite longing in her voice.