So this story is all about Sirius and Lily cheating on James! Well not really cheating, they share a kiss together one night when James isn't around. This is what happens the next day...

Betrayal

Sirius Black sat in the Gryffindor common room and looked over at his best friend James with a guilty expression on his face.

"What is up with you tonight?" James finally asked. "You've been sitting there with a funny look on your face all night!"

"Yeah, well um…" Sirius struggled to come up with a story to tell James to cover the truth. "If you must know I got rejected," he muttered. "That's the first time in my whole six years at Hogwarts that a girl has ever said no to me!" he told James.

"Is that all!" his friend laughed.

He glanced over at Lily Evans who was sitting at the opposite of the common room. Her red hair fell across her face as sat reading a book.

"Well I know how you feel Padfoot," he sighed. "Anyway I think I'm going to go and join Peter in bed."

Sirius sniggered.

"I didn't mean it like that!" James remarked. He shook his head. "I just meant I was going to get an early night like Peter, you knew full well what I meant!"

With one last glance at Lily, James stood up and strode over to the staircase leading to the boys dormitory, casually messing up his hair as he did.

Once James was safely out of the room Sirius hurried over to Lily.

"I'll speak to you later," she coolly, not looking up at him. "Once everyone else is away to bed."

Sirius opened his mouth to protest but seemed to think of better of it and stalked back over to the fire where he collapsed down on a chair.

After an hour of waiting the common room was finally empty and Sirius once more walked over to Lily.

"So what are we going to do?" he asked desperately.

"We aren't going to anything Black. James is your friend, not mine. You're the one that went behind his back," she said simply.

"It wasn't like that!" Sirius protested. "This is as much your fault as it is mine. You know how much he likes you, how he always acts like a big headed buffoon whenever you are around."

Lily looked uncomfortable for a moment. "I never said I would go out with him though," she said.

"But you like him, don't you?"

"I think I did at one time but not now," Lily admitted softly. "If he ever finds out what happened last night…" she tailed off.

"It was a spur of the moment thing. A stupid mistake that should never have happened," Sirius said loudly.

"Was it?" Lily asked.

She looked up at Sirius and her green eyes gazed deeply into his.

"Of c-course it w-wa-was," Sirius stammered uncertainly.

Lily stood up and drew a step closer to him.

"Did it really feel like a mistake to you?" she asked.

"Well – I – From the point of view of James yes it did but apart from that…" Sirius tailed off embarrassedly. "The way I felt last night… I've never had those sorts of feelings for anyone else before."

Lily's cheeks flushed slightly. "Do you want to know why I kept saying no to James?" she asked. "…Because I liked you. You have no idea how jealous I was of all the girls that you have been out with."

"But James?" Sirius asked hoarsely.

"I feel terribly guilty," Lily said shamefully. "But there was a reason I refused to go out with him. I do have feelings for him but nothing like the way I feel about you. It's you that I have always wanted Sirius."

She reached out a petite hand and gently stroked Sirius's cheek.

"I understand the awkward position you are in with James though so we can just forget I ever said anything if you like?" Lily suggested.

Sirius made no reply. He was starting at her with a blank expression on his face.

Lily made to turn away but Sirius grabbed her by the arm and pulled her close to him, kissing her passionately.

"What the hell is going on here!" a voice interrupted.

The pair broke apart and looked around to see James Potter standing with a shocked expression on his face.

"James!" Sirius exclaimed, his face turning deathly pale.

"Remus told me you were still down here so I came down to see what you were up to," James said stonily.

"I can explain-"

"No!" James roared over his best friend.

He swept over to an armchair and sank into it, letting his head fall into his hands.

"How could you Padfoot? What kind of friend would do this?"

"We didn't mean it to happen," Sirius explained quickly.

James ignored him though.

"So what, you've had every other girl in the school so you decided you wanted Lily too did you?"

"It wasn't like that," Lily began.

"Save it!" James snapped. "I'm surprised at you Evans," he looked up at her. "I didn't think you were the type to fall for scumbags like him," he jerked his head at Sirius.

"I'm as much to blame as Sirius is," Lily told him. Tears began to form in her eyes.

"I was the one that came on to him."

James looked as if his face had been smashed against a wall.

"I really like you James but as a good friend. Nothing more, nothing less," Lily rested a hand hesitantly on James's shoulder but he shrugged it off. "I'm so sorry," she whispered.

"Couldn't you just have told me you weren't interested rather than sneaking behind my back and having a fling with someone that was supposed to be my friend?" James asked in a hollow voice.

"I tried to," Lily said gently. "Anytime you asked me out I said no, I thought you would have realized that I wasn't into you in that sort of way."

"I thought you were playing hard to get," James said dully.

"Prongs I never set out to hurt you, neither of us did" Sirius said.

"Shut up!" James yelled. "For once in your life will you just shut your great fat mouth!"

Silence fell in the common room. The only sound was James heavy breathing and Lily's quiet sobs.

"How long have the pair of you been stabbing me in the back then?" James asked at last.

"We haven't," Lily promised. "…It, well, you see it happened last night when you were at your quidditch training. We just sort of kissed. You have no idea how guilty we have both been feeling today."

"Well it didn't stop you from going and snogging again did it!" James snarled.

"It's not like that," Sirius tried to explain. "It's like we have this sort of connection and it just draws us together… I've never felt anything like it before."

"You mean you actually care for each other?" James asked disbelievingly.

Lily slowly nodded, looking down at her feet.

"Sirius is right. I've been feeling it for a long time, I just didn't tell anybody…"

James sighed. "You know one kiss I could probably have forgiven, we all make stupid mistakes now and then but this. The two of you actually falling for each other!"

"Oh James," Lily tried to hug him but he threw her off.

"You actually think that he loves you do you?" he spat. "Sirius doesn't know the meaning of the word. He doesn't love his family and they don't love him either. As for all the girls he has been out with at school well, he probably couldn't tell you their last name, I doubt he would know half of their first names," James said nastily.

"Come on don't be like that," Sirius told him earnestly. "You're probably right about all those other girls but Lily, she is different…"

"Oh yeah, how?" James demanded. "Do you sit for hours a day watching her with her friends, do you dream about her every night, do you get all tongue tied around her, do you try to impress her all the time, do you tell all you friends how great she is? Well? Do you?" he shouted.

Lily's face had turned a deep scarlet colour at hearing James's words. "I feel terrible," she whispered.

"Join the club!" James snapped.

"Look can't we come to some sort of understanding over this?" Sirius asked desperately.

"Understanding! Unders-" James spluttered. He withdrew his wand and slashed it at Sirius who went flying over the common room and crashed into the wall.

Lily gasped before turning and fleeing up to the girls dorm.

"James please," Sirius said weakly pulling himself to his feet. "What happened to all the marauders together forever?"

"I could ask you the same thing," James commented coldly. "Now just go Sirius before I do some real damage to you."

Sirius hesitated before slowly making his way over to the doorway leading up into the tower, limping as he did so.

Before reaching the doorway he turned to face James.

"I've done an awful thing," he admitted. "I know I have but please James, forgive me."

"I don't know if I can right now," James told him quietly. "We were like brothers and then you had to go and ruin it. You know how much I love her and you took her from me without a second thought. You betrayed me…"