Summary: Au where the last words your soulmate says is written on your body.
The words had been with Magnus for longer than anything else, they were a promise and a curse; a promise that someday he would be loved, and a curse that someday he would meet and then lose that person.
Magnus had never let the words affect anything he did, who he loved, but he always wondered if each of them would say the words that were written upon him.
Alexander never asked to see them just as the Shadowhunter never revealed his last words, but every time he left Magnus he would take a moment and a pen and write on his hand the last thing he said before he left. He had explained that it was something silly he, Izzy, and Jace had done as children an acknowledgement that every time they left one another behind could be their last.
When Clary, and Simon joined them they added their words, sometimes Magnus had a teasing remark from Izzy on his forearm for days, or a sarcastic comment from Jace or a question from Clary. It made Magnus feel less frightened of hearing his other half's words because they were joined by others that changed all the time.
A part of Magnus, the part that remembered that he would live forever and his friends would not, promised that when they finally passed he would mark their last words on his skin permanently, they might not be the other half of his soul but perhaps each of them were a piece of it and he never wanted to forget the little family of Shadowhunters that Alexander shared with him.
Alec feared the day he heard his soulmate's last words, every day he hid them from view and he felt like crying, they were beautiful words, if only they weren't the last ones he'd hear from his soulmate's lips.
But Magnus was safe, Magnus was immortal and therefore he didn't have to worry, after all Soulmates weren't for Demons and Warlocks, the Clave had said so and since Magnus had never brought it up or asked about his words Alec could only assume that they were correct.
Alec tried to breath, while Magnus kept trying to heal his wounds, and as Alec coughed up blood he knew it was useless, that no amount of magic would fix what had been broken.
"Mag- Magnus." Alec gasped, "You-you need to stop."
"No, I can't lose you Alexander, I can... I can fix this." Magnus promised.
Alec managed to catch Magnus' hands, stilling them, "Please, Magnus, it's okay."
"It's not, it's not okay." Magnus sobbed out.
"You'll need your strength in case there are more, wait for the others and then," Alec took a wet sounding breath before he could continue, coughing a little, blood filling his mouth and coating his lips as he looked up at the man that held him in his arms, "Then you can fix it, okay?"
"It might be too late, Alexander." Magnus told him.
"Please, Magnus, promise me you'll wait?" Alec asked.
"I promise." Magnus agreed.
There was a long quiet moment while Alec stared up at his lover.
"When I'm better, will you marry me?" Alec asked softly.
Magnus sobbed harder and nodded, "Yes, I'll marry you, Alexander."
Alec smiled up at Magnus lovingly as black filled his vision and he passed out, knowing that Magnus was the other half of his soul.
Magnus was holding Alec tightly when they arrived and he wouldn't release him, Jace knew because he had felt their bond break that Alec was dead and he couldn't bring himself to try taking Alec from Magnus.
"We have to get out of here, Magnus, it's not safe here." Jace said softly as his hand hovered over Magnus' shoulder.
Magnus nodded jerkily and stood carefully, Alec's head against his shoulder as Magnus lifted him up in his arms.
Magnus was permitted to attend Alexander's funeral, the words around his wrist, the words Alexander had spoken to him, on display. Magnus had allowed Alexander to drag him into the little tradition he had with his siblings but he had never allowed those words to be penned on his left arm, for them it was always the right, or if Alexander was feeling particularly bold on his chest or back, the left Magnus had always reasoned in the privacy of his own mind was for his soulmate only.
When Izzy had shown up to comfort Magnus or come to his seeking comfort, Magnus wasn't sure, she had found him staring at the blue words on his skin, Magnus had never allowed them to use blue ink, Izzy always used red, Jace gold, Clary a pretty purple color and Simon had used green, Alexander had just used the nearest pen, sometimes green, sometimes orange, when Magnus had realized Alexander had used whatever was closest he'd taken to carrying a silver colored pen with him, for when he saw Alexander at the Institute so he could cross out the morning's farewell and pen the newest one.
"Did- Are those Alec's words?" She had asked and then just held him when he nodded.
Magnus had always known he'd lose his soulmate before they wed but it hurt more than he had expected because he hadn't expected Alexander to be his soul's other half, he thought they would have a chance for that, marriage. At his lowest moments following Alexander's death Magnus wished that Alexander wasn't his soulmate, because then maybe everything would have gone differently, maybe they would have lived a long happy life together and Magnus would never have had to say goodbye to Alexander so soon.