You weren't sure how or when you started crushing on Sirius Black, but it filled you with unmistakable panic.
It was common knowledge that you and Sirius didn't get along well. You hated his arrogant attitude and flirty personality. He hated you because according to him, you were "an obnoxious know-it-all". Needless to say, neither of you made any effort to be friends. You were barely civil, and the only reason you tired was because Lily Evans, your best friend, was dating James Potter, his best friend.
"I hate him," you said through gritted teeth, glaring daggers at the back of Sirius's head. Lily sighed before dropping her copy of Advanced Potions, Grade 7 and turning to look at you. Both of you were sitting under a tree by the Great Lake. The sun was shining bright despite the cold air, and it made you feel drowsy. You would have been perfectly content if that insufferable idiot hadn't shown up.
"I know, you already said that six times." She looked at you, amusement sparkling in her eyes as you continued to glare at Sirius, who was laughing at something James had just said. "Y'know, I'm surprised he hasn't dropped dead yet, considering how much poison there is in your eyes."
You snorted. "I'm more disappointed than surprised."
You continued looking at the boys across from you at the other side of the lake, only to see them slowly trudging over to where you sat.
"Oh no." You tried to get up and leave, but Lily grabbed your arm. You whined in protest.
"Stop being melodramatic. Being in the same vicinity as him won't give you a disease." She pulled you back down on the grass beside her.
"Actually, I'm pretty sure it will."
Before Lily could scold you again, the boys had reached you, James flopping down next to Lily and planting a sloppy kiss to her cheek, making her giggle and push him away.
The rest of them sat down facing you, Remus giving you a smile which you gladly returned. You liked Remus. He was smart and witty, a fun person to hang out with. Your smile immediately got replaced by a scowl when your eyes met stormy grey ones.
"Black."
"Y/L/N."
You caught Lily's eye before you could throw a scalding comment his way. She was shaking her head, giving you a please, not again look. So you shut your mouth and returned to your book.

You hadn't realized how your feelings for Sirius changed until one day he didn't show up to any of his classes. He was sick, according to James, and for a split second, you felt genuine concern for him before you shook your head, thinking what the fuck.
You hadn't realized your feelings for Sirius until he laughed at his own joke, something you suddenly found endearing rather than annoying.
You hadn't realized your feelings for Sirius until he his hair fell in his face while he worked on an assignment, and you had to physically stop yourself from tucking it behind his ear.
You hadn't realized your feelings for Sirius until they consumed you completely, until he was all that you could think of, until you accepted the fact that you could never tell him. He would never feel the same, and you'd have to take this secret to the grave with you.

Now here you were in your seventh year Potions class, panicked and angry when Slughorn decided to seat Sirius next to you. Why he wanted to do that, you had no clue, so instead you settled with cussing him out in your brain.
Taking a deep breath to control your anger, you tried to focus on the lecture as Sirius continued to tap his quill on the desk. You gritted your teeth, wanting nothing more than to grab the quill from his hand and break it into two. So you did just that.
Sirius stared at you, mouth open as you handed the broken pieces back to him, giving him a fake sweet smile. He sneered before turning to his bag, and pulling out another quill, he began tapping it on his desk.
You were glad that Professor Slughorn finally turned to face the class after he finished writing the main point of the day's lecture on the board. Had he stayed turned with his back to the class, you would have slapped Sirius, and you were in no mood of getting yet another detention.
Thankfully, Sirius stopped his tapping as the teacher started to walk around the room, placing a vial of clear-looking liquid at each table. As he returned to the front, he started to speak.
"Today's topic is something I'm sure you lot will enjoy learning about," he said. "Sitting before you on your tables, is one modest vial of the most powerful love potion on the planet; Amortentia."
You leaned forward to stare at the bottle in intrigue. You had never seen Amortentia before, which was normal since it was an illegal brew. Sirius was staring at the little bottle with interest that almost paralleled yours. Slughorn continued.
"Amortentia's biggest distinguishing feature is that it has the ability to smell like something - or someone - you love. As it is illegal to brew, you will not be brewing this potion in my class, however, I have provided you samples to examine. You must all know how to recognize Amortentia by how it smells to you."
As Slughorn settled in his seat, the students started uncorking bottles and taking a whiff. You leaned forward, wanting nothing more than to know what Amortentia smelled like for you. You imagined the smell of books, or maybe rain. Maybe even a fire crackling in a forest. But as you took a whiff, you frowned.
"Could you move over? I can't smell anything over the scent of your horrendous shampoo."
Sirius narrowed his eyes and raised an eyebrow. "At least I didn't drench myself in perfume before I came to class!"
Your mouth open in protest. "I'm not wearing any perfume, dim-wit!"
"Well I didn't wash my hair today, smartass!"
A cackle from the table in front of you broke your jabs. You looked up to see that James and Remus had turned around in their seats, James gasping for breath and Remus with his mouth wide open and a look of realization on his face.
"What?" You snapped, annoyed to no end.
"That's your Amortentia. Your Amortentia smells like Sirius's shampoo...." He trailed off as he looked between you and Sirius.
"And Sirius's Amortentia smells like Y/N's perfume!" James chimed in, face now red from the effort of holding back laughter.
Your body ran cold at the implications of their words. You didn't dare to look at Sirius, too afraid to know what his face might look like. Now he knows how I feel. You wanted nothing more than for the ground to open up and swallow you whole. Your secret was out.
The rest of the period was spent in silence, James making an occasional joke about the revelations, making you turn red hot at every word. It was only when class ended and you were walking back to your common room that your processed the other half of today's fiasco. What you realised made you gasp.
Sirius's Amortentia smelled like you. Sirius Black loved you.
You stood in the middle of the corridor, mouth open and breaths heavy. You couldn't believe it, couldn't even grasp the concept of Sirius feeling the same way. You had known him for almost 7 years now. Yet he hadn't said a word.
Your shock was quickly replaced by anger. He hadn't said a word! All this time you've felt like absolute crap trying to suppress your feelings, and he didn't even bother telling you! At the back of your head, you knew you hadn't told him either. But blaming Sirius for your life's failures had become a force of habit, so you went along with your anger.
In your moment of hotheadedness, you let your feet carry you directly to your common room. By now your mind had stopped forming rational thought. You spat out the password and climbed in.
"SIRIUS BLACK!" Five heads turned as the boys and Lily looked at you from their place on the couches next to the fireplace. Sirius raised his eyebrows and stood up, his body tense.
"How dare you!" You continued screaming, stomping over to where he stood. Your fists made contact with his chest as you hit him over and over, pushing him slightly.
"Fuck you, Black. Literally... FUCK. YOU. You insufferable twat, with your stupid eyes, and your stupid face and your fucking stupid hair, fuck you and your perfect little-"
Sirius grabbed your wrists, holding them down on your side. Then, with a look of absolute determination on his face, he tugged you closer and pressed his lips against yours in a searing kiss.
The common room probably erupted into gasps and shouts at his action, but none of it registered over the feeling of Sirius's lips on yours. His hands found your hips, pulling you closer as his tongue crept into your mouth. Your fingers tangled into his hair, and bliss overtook your body. Heart thumping and face hot, with your breaths and sighs mixing together, you kissed each other like it was the last time you'd kiss. Like starved souls finally uniting. You kissed like you wanted to make up for seven wasted years, like you'd never see each other again.
You cursed biology for having to pull away, your need for air was too strong. Sirius looked at you, a million different emotions in his eyes. You pulled him closer, arms wrapping around each other, sinking into his body heat. He didn't have to say anything. There was nothing left to say. Amortentia had said it all for you.