Written For:

- Day 15 of 366 Days of Writing Challenge: Crush

- February Event: Teamwork Exercise: (plot/action) Receiving a card/gift from a Secret Admirer, (object) Card/Love Letter

- Gringotts Prompt Bank/Pairings: Narcissa/Regulus

- Gringotts Prompt Bank/Poems Porn: "I wonder how biology can explain the physical pain you feel in our chest when all you want to do is be with someone."

- Gringotts Prompt Bank/Frat Pack: "Are you crying?" / "Am I crying? I'm not crying! You are."

- Gringotts Prompt Bank/Alliterating Phrases: 'Down in the Dumps'

- Gringotts Prompt Bank/Adjectives: Defensive, Interesting, Sharp

Pairings/Characters: Narcissa/Lucius, Regulus, Sirius

Word Count: 640


Biology

No one lives forever, but that's no reason to give up. Don't you wanna fall in love?

Regulus clutched the card to his chest as he wandered through the hallways of Grimmauld Place. He had a sealed envelope in his pocket, containing a Valentines card for his crush—hopefully, the person who had sent him his own card.

As he stood outside Narcissa's bedroom, he took another peek at the curly script in his card. 'To Regulus. Happy Valentines Day! Love from your secret admirer.' He blushed, trying to imagine Narcissa sitting over her desk and writing out the card to him the night before, and sliding it under his door. For a moment, Regulus considered sliding the card he'd written to Narcissa under her door, but he took a deep breath. He had to be a man about this.

Clearing his throat, he knocked on the door briefly and then entered.

What he saw before him came as a shock. Narcissa was sprawled out on her bed, straddling a platinum-haired bloke who Regulus recognised as Lucius Malfoy. She was wearing nothing but her skimpy blue underwear, and was leaning over Lucius, sticking out her rear provocatively.

They both snapped their heads to face Regulus, and Narcissa slipped down from atop Lucius and wrapped herself in the sheets. Once she had composed herself, she glared at her cousin. "What the hell are you doing, just walking in here!?"

"I...I was..." Regulus could feel his face glowing. He held out the sealed card, stammering. "I was...just giving you a...a card...and I wanted...wanted to say..."

"Spit it out," Lucius probed.

"...Thanks for the card," mumbled Regulus, dropping the card for Narcissa to the floor. There was a brief silence, which was broken by Narcissa's sudden, haughty laugh.

"I didn't send you a card."

Unable to look Narcissa in the eye, Regulus spun on his heel and rushed out of the bedroom, hurling down the stairs and into the dining room. He could hear Narcissa and Lucius laughing upstairs, and he closed the heavy oak door behind him, rubbing his eyes fiercely.

When he had cleared the tears from his vision, he spotted his older brother sitting at the table, with a textbook open in front of him. He was staring up at Regulus, an eyebrow raised.

"Are you crying?"

Regulus glared at Sirius. "Am I crying? I'm not crying! You are," he snapped, and Sirius rolled his eyes, turning his attention back to the textbook. Regulus sat opposite him quietly, and took a glance at Sirius's book, noticing that none of the pictures were moving. It was a Muggle book.

"What's got you down in the dumps?" Sirius questioned, turning the page.

Regulus shrugged. "It doesn't matter."

"You gave Narcissa a card, didn't you?"

"Only because she gave me a card!" snapped Regulus defensively. Sirius met Regulus's gaze again.

"You idiot. Narcissa didn't give you that card."

"Well, who did?"

"Didn't you notice that it was in your trunk before you even came home from Hogwarts? My guess is that it's someone in your dorm," Sirius paused, lowering his voice. "My money is on Barty."

Regulus opened his mouth to retort, but found that no words could be found. He sat back in his chair, suddenly feeling like quite an idiot. "What are you reading?" he asked, changing the subject.

"A Muggle textbook," Sirius replied. "Lily Evans gave it to me—but don't tell Mum. It's called 'Biology', something that the Muggles learn in their school. It's mainly about the human body. Quite interesting, actually."

Regulus sighed. "I wonder how much biology can explain the physical pain you feel in our chest when all you want to do is be with someone."

"Pass me the sick bucket," muttered Sirius, closing the textbook sharply and throwing it at his brother.