Summary: When Lily comes home with an engagement ring from James Potter, Petunia tries to convince her that she's making a terrible mistake, and a friendship is finally shattered. One-shot.

Disclaimer: I don't own Harry Potter or any of J.K. Rowling's fabulous characters. Go sue someone else.

Petunia had felt the gap between her and her sister growing larger through the years as she was left behind time and again, watching the Hogwarts Express pull away from Platform 9 and ¾, and still larger when Lily came back with a shiny, expensive engagement ring. Petunia thought that if she could only convince Lily of her grave error in choosing to marry James, perhaps their friendship could be restored to what it had been seven years ago. It was irrational, she knew, but knowing that didn't eliminate the feeling.

"You shouldn't marry him, Lily," Petunia said quietly when the two of them were alone in Lily's old room.

"Oh?" laughed the redhead, arching an eyebrow at her younger sister. "Whyever not?"

"He can have anyone else he wants."

Lily smiled even wider, her voice becoming almost sing-song. "Exactly! And he chose me. Isn't that sweet?"

Petunia sighed in irritation. Her eighteen-year-old sister was clearly head-over-heels in love with the conceited Potter boy she was about to marry. But Petunia had to make her realize what a mistake she was making. She had to. "Lily, listen! James may be able to get anyone he wants, but Severus can't. Severus won't. He loves you, Lily!"

Lily grew sober at the mention of her former best friend, as Petunia had known it would. "Don't talk about him, Tuney."

"Why not? Is it because he's not as handsome as James? I thought you were better than that."

"It's not that!" protested Lily with a hurt look. "You know I don't care about things like that. It's just that we're not friends anymore. Haven't been in ages."

"So you've told me, but you never mentioned the reason your friendship ended so abruptly."

"The Dark Arts, Tuney. He was getting mixed up in the wrong crowd. Severus was sorted into Slytherin for a reason, and I was a fool not to have realized that before our seventh year. Besides," she added with a scowl, "he called me a Mudblood."

"But didn't he also spend half the night waiting outside the Gryffindor Common Room for the chance to apologize to you?"

Lily's face colored a little at the memory. "Yes, but that doesn't mean anything. I bet he'll turn Death Eater, you wait and see. I refuse to even associate with someone who loves the Dark Arts as much as he does."

"He'd give it up for you in a heartbeat if you just asked, you know."

"No he wouldn't," Lily countered stubbornly. "And besides, why are you suddenly on his side? I thought you didn't like 'our kind'!"

"I don't," said Petunia truthfully. "But one thing I hate more than magic is to see a friendship and potential love die because one person is too stubborn to see how much the other cares for her!"

Lily jumped; Petunia's voice had risen to a shout. With a visible effort, the younger of the two sisters took a deep breath. "Look, I hung around Severus as much as you did before you both went to that school. I know he seems arrogant and comes off as quite rude, but he's loved you since you were eight. Just give him another chance!"

Her sister's face hardened. "No, Petunia, I will not. I've given that git enough chances."

Petunia was shocked; Lily hadn't called her by her real name in longer than she could remember. She opened her mouth, then closed it when she realized nothing she could say would make Lily change her mind. "Fine," she said coldly, dripping sarcasm, "go marry your perfectly pompous Potter. Ignore the man who's loved you for most of his life. I'm sure you and James will make a lovely couple. You'll produce beautiful children who grow up to be little scoundrels that crush the dreams of others, just like their parents."

With that, she left her sister standing there glaring, the gap between the two of them wider than ever, beyond repair.