Harry James Potter, who had only just begun to recover from the aftermath of defeating the most feared Dark Lord in well over a century (Grindlewald had been downgraded due to his dealings with an insane muggle) after almost a year on the run, had not expected to find himself in an alternate version of his old home on Privet drive sitting across from his mother who was looking at him with a pinched expression that he had usually associated with his Aunt Petunia.
Looking around the living-room, he could confidently say that had their positions been reversed, his mother would never have treated Petunia's child the way that Petunia had treated hers. In every family portrait, there were two boys, a dark auburn haired boy with almost no neck who was a roughly even mix of muscle and fat, and a smaller, slightly pudgy boy who bore a striking resemblance to Pettigrew that had a rather familiar scar on his forehead.
It had been for this slightly pudgy child who looked a bit like Neville had during their first year that he had been called to this strange world. When he had first found himself in the summoning circle, he had pulled his wand believing the situation to have been a trap laid by the few remaining Death Eaters that had yet to be rounded up. After his spell had rebounded at the edge of the circle and almost hit him, he managed to calm himself down if only so he didn't accidentally kill himself. It was only after Lily Dursley had told him a story that was so insane that it could possibly be true and secured several vows that he would not harm her family and friends that he had been released from the circle.
He was now sitting on a rather delicate looking chair in a rather tastefully decorated living-room pretending to drink tea that was rapidly going cold while he stared at the woman who in another lifetime had been his mother, and wondering if he wanted to help the son of a traitor fufill a destiny that he wouldn't wish on his worst enemy. Deciding that the silence was becoming too oppressive, he asked the other question that had been bothering him.
"Er...What exactly happened between you and my father?" he asked, fidgeting and hoping the answer wouldn't be too painful.
Lily's scowl and cold response detailing every last one of James Potter's failings told him that he had clearly asked the wrong question.
"So," Lily said in a falsely sweet tone as she looked like Petunia going in for the kill "How exactly did you end up being the Boy-Who-Lived?"
He winced. She knew he didn't want to talk about that. Apparently that was precisely why she had asked.
"My parents, Your and James Potter's counterparts in my universe, got married right out of Hogwarts. They joined the Order of the Pheonix. You obviously know about the prophesy. When they went into hiding, they decided to go under the Fidelious. They had planned to use my Godfather Sirius as Secret Keeper, but he pointed out that he was too obvious a choice and would work better as a decoy leading the Death Eaters on a merry chase away from the true Secret Keeper. Pettigrew became the Secret Keeper, and he obviously didn't have whatever it was that caused him to refuse Voldemort, much less defy him three times. I bet you can guess the rest, just substitute a James Potter who tried to hold off Voldemort for Pettigrew, and you for Petunia as the sacrifice." Harry replied.
"So you lived with Black then." Lily said getting that pinched expression on her face once more. Since Black had survived, it was a forgone conclusion that he had raised Harry to be as cruel as he and his jerk of a father were.
"No. Everyone believed that Sirius was the Secret Keeper. Sirius went after Pettigrew who yelled that Sirius betrayed my parents, and blew up a street killing a dozen muggles before turning into a rat and escaping into the sewers. When the Aurors came for Sirius they believed that he had killed the muggles as well as betrayed my parents. He was thrown into Azkaban without a trial. I was sent to live with my Aunt Petunia and Uncle Vernon." Harry replied.
"Well they at least seem to have raised you properly." Lily said.
"Yeah, sure, making me sleep in a cupboard for ten years, feeding me scraps, having me do all of the chores while their son Dudley grew to the size of a whale while he sat around doing nothing, that was real proper." Harry retorted "The nicest thing that any one of them said to me was that I'm not a waste of space, and that was Dudley who said it."
There was the sound of china breaking as Lily's teacup fell to the floor as she stood up absolutely furious.
"LIAR!" she roared. "If I could do the spell again and get someone else, I'd send you away in an instant!"
Seeing the look of pain in Harry's eyes before he ran off, she realized that everything he had said was true. There had been a world where she had been so selfish that she had uncaringly torn Petunia away from her true love so she could be with that Jerk James Potter. There was a world where Petunia was forced to marry Vernon in order to pay the debt that had been accrued when the Dursleys had payed her Hogwarts tuition. Her family hadn't had the money to pay the Dursleys, and since Vernon - who needed half a dozen calming potions to be manageable - was unlikely to find a wife on his own the agreement had been for one of the Evans daughters to marry him in order for all debts to be forgiven.
There was a world in which she had totally ruined Petunia's life, and her own son had been forced to pay for it.