So I was in the middle of writing my other story A Kittens Wish and I got this idea. What happens when a shadowhunter swears on the angel and then breaks it? What if Alec swore to never hurt Magnus? I was like "Yes! I could totally make a story out of that!" But to be honest I have no idea where this is going or even if Alec should die or not so please review or PM me and let me know what you think, want to happen, or if I should continue it! This is really angsty because i'm in an angsty mood and I honestly don't know how this story could be happy or fluffy but I hope you like it anyway!

Warning: This story contains spoilers for City of Lost Souls (I think)

Alec collapsed to his knees in the subway, tears streaming down his face as his reason to live walked away from him. How could he be so stupid!? Going behind Magnus's back to talk to Camille, how could he break Magnus's trust like that!? Though one part of his mind whispered that Magnus should have listened. Should have opened up more and trusted him. Magnus knew everything there was to know about him yet Alec didn't know anything from his past other than what happened to his parents.

To be honest it hurt. It hurt that Magnus didn't open up to him, didn't let him explain that he never wanted Magnus to be a mortal in the first place, but the thing that hurt the most was the fact that Magnus trusted Camille more than Alec. Camille had told Magnus that Alec was seeing her to take away his immortality, and Magnus believed it instantly not even thinking for a minute that maybe Alec was seeing Camille for a different reason. Yet even though Magnus shared the blame just as much as him he couldn't help but hate himself and what he did to Magnus. He hurt him. He swore to Magnus that he would never hurt him and he did.

Alec gasped and clutched at his chest where it felt like his heart was splitting in two. This wasn't right. Yes, he felt so heartbroken about Magnus he couldn't see how he would be able to keep going but his heart literally hurt. The pain was excruciatingly painful, so much it was hard to keep breathing. Gasping for air that wasn't filling his lungs Alec started to see black spots in his vision. Maybe this was what drowning felt like.

Alec clawed at his chest trying to make the unbearable pain stop until finally Alec's vision went black and he collapsed to the dirty floor of the abandoned subway tunnel.

Alec groaned and rolled over. His whole body ached and felt just plain wrong, especially his heart, and his senses where clouded with the smell antiseptic and bleach. Was he in the infirmary? Slowly, he forced open his eyes that felt as if they had been glued shut and looked around, trying not to move his pounding head.

His assumption was affirmed as he looked around the white walls and hard beds of the institute infirmary. In the chair beside his bed sat his sister who was currently asleep with her head propped up by her hand and her black hair falling around her arms like a blanket. Worry lines where etched on her face and Alec frowned. What would make her so worried?

His mind was suddenly filled with memories of last night and Alec could barely hold back his tears. Him and Magnus where broken up. Alec forced a smile on his face that probably looked more like a grimace as Isabelle started to stir. She opened her eyes and they widened when she saw that he was awake. She was hugging him tightly in an instant as if she would never let go. Alec wrapped his arms around his sister trying not to show how much pain he was in.

Isabelle started rambling worriedly, still not pulling away from the hug. "Oh Alec, we where so worried! You said you would come over this morning at seven to train with Jace but you didn't come so we called Magnus and he didn't answer. We went to his apartment and he wouldn't answer the door either so Jace grabbed a sweater from you're room and put a tracking rune on it and it said you where in the abandoned subway and so we ran over there and you where laying on the floor passed out and breathing erratically! What happened!?" She said this in all one breath and Alec had trouble keeping up with her.

He hesitated. He really didn't want to tell her that Magnus and he had broken up, because it felt as if he said the words it would make it true. And Isabelle would of course want to kill Magnus or want to know what happened or both and Alec didn't want to explain that either. As for what happened to him, Alec didn't know himself and he didn't want to worry his siblings.

Isabelle pulled back from the hug and glared at him obviously reading his hesitation. "Alexander Gideon Lightwood, you are going to tell everything that happened right now, and I mean EVERYTHING. I want to know why you where at the subway, what happened, and why Magnus isn't talking to us, NOW."

Alec sighed. His sister wouldn't leave him alone until he told her everything and would know if he left anything out. He tiredly began to explain everything and prayed she wouldn't hate him when he was done.

Wow. I think I just hurt myself writing that. I'm not entirely sure what should happen to him or what the side effects should be of breaking the promise or if he and Magnus should get back together so I would really appreciate it if you reviewed or PM me! I hope you liked it (Even though it was very angsty) XD