My first Mortal Instruments fanfiction! They're probably very OOC, but I did my best and I could not get this idea out of my head. The cover image is by Serena-Neko on deviantart

They did this sometimes. They would just sit and listen to their heartbeats and Magnus would hum nonsense into Alec's ear. Alec would play with the buttons on Magnus' shirt or gently tug at his hair. They'd hold hands and just savor the time they had together. It was a lazy Sunday, there was nothing else to it. Alec's head was on Magnus' chest and their legs were tangled together at the end of Magnus' huge, fluffy, pink couch. Alec loved these moments, where it didn't matter that Magnus was immortal or that he fought demons for a living. It didn't have to matter because they were alone, just the two of them.

But Magnus' mind wasn't in the same place. His head was whirling and Alec's fingers on his scalp wasn't having it's usual calming effect. He couldn't get over the faster beat of Alec's heart. He had so often wondered what would happen if he gave it up and grew old with Alec. What would happen if he quickened the beating of his own heart to match his lover's. He had never wanted so badly to be mortal. He wanted to spend the rest of his life with Alec.

"I can't make you immortal." Magnus blurted suddenly, causing Alec's eyebrows to lift, "Well not without making you a vampire, which probably wouldn't be the best." Alec was still looking at him funny, like he couldn't grasp the words that were tumbling out of Magnus' mouth. The warlock panicked, trying to explain that he'd tried his hardest but it just wasn't possible. But Alec wouldn't put that eyebrow down, it kept rising into his hairline and making Magnus' heartbeat run away. That eyebrow would be the death of him, it was certain. He stood up and started pacing, still trying to explain how hard he'd tried and how much research he'd done.

"There was that time when I put the potion into your food, but that didn't have any effect and you didn't notice-"

"Woah," Alec stood up, grabbing his shoulders and turning Magnus to face him. The eyebrow had not returned the it's normal place, it was still high on Alec's forehead and doing unspeakable things to Magnus' pulse. "You put something in my food?"

"Well..." Magnus blushed, "maybe?" he didn't want Alec to be mad, but he also didn't want to get his hopes up for something so unlikely. Magnus wasn't sure when he started rambling again, but he certainly stopped when Alec's lips pressed into his.

It was like a scene in a movie, his words turning to mush and his eyes fluttering shut. Alec's hands had found their way back into his hair, like they always did, and the blue-eyed boy kept pulling Magnus closer, like they could become one person if he pulled hard enough. Alec's lips were always surprisingly soft and cold, molding to fit Magnus' whenever they collided, whether it be in passion or just peace. When oxygen became necessary and Magnus' brain had successfully been liquidized, they broke the kiss. Pressing their foreheads together and letting his arms fall to Magnus' shoulders, Alec smiled at the dazed expression on his warlock's face.

"I don't care about being immortal Magnus, I just want to spend as much time with you as my lifetime will allow." He punctuated his loving, slightly melancholy sentence by sweeping Magnus' hair out of his eyes and trailing his fingertips lightly over the caramel skin of his sharp jawline.

Magnus scowled, ignoring the shiver that ran down his back when Alec did that. He didn't care if Alec wanted to be immortal, he was selfish. Alec's lifetime was never going to be enough for Magnus and he didn't want to spend forever being alone. He didn't want Alec to think he was trivial. Magnus didn't want the teenager to be a chapter in his life, he wanted him to be the story, the happy ending he needed for so long. He knew there was another way to solve this, a solution Magnus had never thought of using before now.

"I can become mortal." Magnus said, looking into Alec's wide eyes.

"Magnus-"

He sighed, "I'm serious Alec. I could perform one spell, that's all it would take for us to grow old together. We can complain about arthritis and hooligans. We can bitch about being old. We can die together." Magnus could see it in his mind's eye, the two of them sitting together and falling apart slowly, willing to be together until the end. That was the way love was supposed to be, wasn't it? Weren't they supposed to hold hands, die as old men? He had never wanted that until he met Alec. Everything had changed when he met Alec.

"Hooligans?" Alec asked, his lips quirking in the way they always did when he was trying not to laugh. His face became serious again as his voice dropped, "Magnus, I can't ask you to do that."

Shaking his head, Magnus asked the question he needed answered. "But do you want it? Do you want to spend the rest of your life with me? I can't give you forever, but I can take it away, so we can live out our years together." It sounded almost silly, the ostentatious warlock and the self-conscious shadowhunter becoming domestic. But somehow, knowing it was possible, knowing that they could have that perfect future, made Magnus want to buy a house. He wanted to argue with Alec over paint colors, to spend days arranging furniture and buying paintings to put in their house.

Biting his lip, Alec said the only answer he could give to that question, the only one he could imagine. "Yes." The word itself was quiet, whispered into a quiet room, but it spoke volumes. It opened up doors that had been firmly closed. It started a future no one thought they could have together. That one quiet, short word had started their happily ever after. Magnus was willing to give Alec anything he wanted, no matter what the cost.

Grinning, the warlock pressed his lips against Alec's forehead, then his nose and then his lips. There was something sweet about it, the way Magnus liked kissing Alec's face. It was weird, but all the same, sweet. They stood there for a moment, just breathing and smiling, Magnus imagining their heartbeats going the same pace and all the things it could mean for their future.

"I'm scared." Magnus wasn't sure he meant to say that aloud, but it was out there now. Alec didn't look at him with the pity he was expecting, but instead with the love and strength he needed. Alec had a way of doing that, taking Magnus by surprise and always giving him what he needed.

Alec's eyes never left Magnus', "I would be surprised if you weren't. But I'll be here. I'll always be here." Magnus bit his lip, wanting more than anything for those words to be true. But 'always' was a big promise, a promise that usually didn't last.

"That's not what I'm scared of." He didn't mean to say that either, but the words wouldn't stop falling from his lips. Magnus glared at the ground, picturing words jumbled there and cursing them for betraying him. How dare they leave his brain, Magnus was certain now that he'd told them to stay put.

"What is it then?"

"Nothing." It was like Magnus had finally gotten control over his voice and he finally stopped blurting all his feelings to Alec. He could swear he was relieved, but the tension had yet to leave his shoulders. Because he was scared, he was so damn scared.

Rolling his bright blue eyes, Alec shook his head slightly, not buying Magnus' excuse for even a second. "Magnus. That's my answer and it's also bullshit. What's going on?"

"I'm scared you're going to realize I've got nothing to give you. I've always been young and beautiful, I lure people in with my looks and that's usually the only reason they stay." He admitted, if he was going to give his immortality for Alec, Magnus had to start being honest with him. It was hard. Opening up to someone completely was always risky, but Alec's hands in his own gave him courage and reminded him why he was doing it.

"I don't like you simply because you're attractive." The shadowhunter wasn't annoyed by this comment and he didn't say it in that exasperated tone he usually used. Alec knew how worried Magnus was, he could hear it in the tremor in his voice, the quiver in his words. So his response was soft and kind, urging Magnus to meet his eyes again, something the warlock did reluctantly.

But even after they made eye contact, Magnus wasn't convinced, he was still standing his ground, as though Magnus was trying to convince him that Alec didn't love him. "You say that now, when that's not an issue! But what about when I'm old and I have nothing left to give. All I have is time Alec and even if I give you all of it, I'm scared it won't be enough. You deserve so much more." His voice cracked on the last sentence. Because no matter what Alec had said in the past, this one moment showed that Magnus wasn't confident. He flashed arrogant smiles and suggestive comments but he was scared. He had always been scared. Magnus was scared that he would one day find something that he wanted to keep, wanted to hide from the world and hold onto forever. He had found his something, he had found his Alec. Alec who was perfect, funny, strong and brave, who put up with his antics and insanity. But he was far too good for him, because Magnus could always hear it in his head, the voice from his childhood, telling him that he was a monster and that he didn't deserve the happy ending Alec offered.

"Magnus Bane," Alec's voice was serious and stern, Magnus looking up at him and opening his mouth to continue his rant at the same time, "No. You're going to listen to me for once." Blushing, Magnus closed his mouth and nodded, making Alec smile slightly. "I love you. Not because you're beautiful on the outside, but because your inside is pretty beautiful too. The way your eyes light up when something makes you happy. The way you hum while you do your makeup because you don't like the way the radio picks songs for you and you're too lazy to buy a computer or an ipod. I love the way you eat everything I make while I'm making it. The way you put your head on my shoulder and dip your fingers into the cake batter like I can't see you. I love the way you give snarky responses, especially when you're flattered or embarrassed. The way you stretch like a cat in the morning and your back cracks in that way that I'm ninety percent sure isn't healthy. The way you get really jealous when we're out and start biting my neck just hard enough to leave marks. The way you sneak pieces of blue clothing into my drawers like I'm not going to see them. The way you kiss my nose before I go on a mission. The way you always wait for me, with a cup of tea that has long-since gone cold and a movie you want us to watch, even though you know I'm going to fall asleep.

"You have habits that you don't even see, small bits and pieces that make you who you are. You're not perfect, but you're all that I want. You're more than I deserve and I'm still wondering why you like me. I don't care if I grow old and you stay young, I don't care if you grow tired of me and dump me when I get old. I don't care if you decide to grow old with me. Because no matter what happens, you're the snarky, sarcastic, sexy warlock that lured me in with his looks and convinced me to stay with everything else. I love you Magnus Bane and I will until the day that I die. You have my support no matter what you choose." Alec finished his speech, taking a big breath and giving Magnus that look of pure love that always took his breath away.

When Magnus finally regained motor control and got his brain back in order, he gave the teenager a watery smile. "When did you become a hero from a romantic comedy?" He didn't want to think of all the things that Alec had said, that he had noticed. Because it pained him, the knowledge that someone as perfect as Alec could love him.

"When I fell in love with you." Alec responded with a grin, making Magnus laugh and cry at the same time. Tears beginning to rush down his face as his fears melted and for the first time, Magnus Bane was ready to be mortal. He was truly ready. After a speech like the one Alec gave, who wouldn't be? They could do this. They would do this, the only way they knew possible. Together.

Alec's hand reached up to brush away Magnus' tears, but the warlock caught it halfway and kissed his knuckles instead. He stroked the scar that marred the back of Alec's pale hands. "We're getting sappy aren't we?" This caused them both to laugh, Alec leaning in to steal a quick kiss from his boyfriend. Just pressing their mouths together for a second, to taste the salt from Magnus' tears and feel the smile against his lips.

"Is that a bad thing?" Alec asked, wrapping his arms around Magnus' neck and letting the taller of the two wind his arms around Alec's waist.

Laughing, Magnus shook his head. "Let's grow old together."

Even after the speech and Magnus' emotional waterfall, Alec still didn't want to pressure him. "Really? I don't want to-" It was Magnus' turn to press his lips to Alec's and shut him up. They savoured the kiss for a little longer, knowing that it was going to be the first in a lifetime of kisses.

"I've been young and beautiful for a long time. I've met kings, prostitutes, demons, shadowhunters, and even the occasional angel." Alec's eyebrow went up at that one, almost stopping Magnus' heart. "But I've never met anyone like you Alexander. You are not my first, but you are my last. I will love you back, until we die." Smirking at Alec, he finished with a thoughtful. "I've always wanted a knight in shining armour." He looped his fingers through Alec's belt loops, pressing their hips and foreheads together once more.

Alec's eyes were bright, filled with happiness and that inexplicable lightness that comes hand in hand with love. "You're going to have to make do because I'm a teenager usually covered in demon slime."

Magnus grinned, shaking his head and diving in for one more kiss. "Alexander, when are you going to learn? You are so much more than that."

They did this sometimes. They wouldn't be able to do it forever, but that was okay. They would listen to their heartbeats until they stopped and they would always be together. Because that's what love is all about.

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