Magnus felt that his numbers were mocking him now. He'd forgotten when his birthday was and if it wasn't for the fact that from one day to the next his number changed, he would never know. He still had years to wait, so really, why should he bother looking at his numbers anymore.

He remembered Will and Jem and Tessa, all those years ago. Sitting in the library of the London Institute, Will and Jem arguing over what the next step in the plan should be and Tessa watching with love and laughter in her eyes.

Magnus was exhausted from the magic needed to fix Will's broken arm, and to be honest he didn't want to see if Tessa finally had control over her magic. It was a weird dynamic between the three of them that Magnus loved to watch. When Magnus had met Tessa, he could see that there was a connection between the three of them, but it wasn't until later that Magnus understood why.

Tessa was one of those rare cases of multiple soulmates, but fate had a wicked sense of humour to make them Parabatai. The numbers over her heart were only hours apart. She had met Jem shortly after coming to the London Institute and met Will a few hours later, once Jem and retrieved him from where he was brooding in his room.

Magnus had asked Tessa how she felt about it, and all she had said was that at least they were friends. It took Magnus quite a whole to understand the dynamic, even longer not to look at them all like they completely insane. Magnus had dabbled in multiple partners before, but never in the relationship category, it was too weird.

But then Magnus had found out about Jem and his reliance on Yin Fen. 'Maybe fate thought he should have someone love him before he dies', Magnus had thought before he truly looked at them. Even if Jem had died five minutes after meeting Tessa he would have known love, would have been loved. Will made sure of that.

Magnus was broken out of his thoughts when Tessa stood up and yelled at the boys arguing over a map of London.

"You're acting like children, and when you decide to act like adults and Shadowhunters, come find me." She walked out the door with a flick of her wrist that sent the ottoman in the corner flying through the window.

Magnus would have been impressed if that was actually what she wanted to happen. Jem and Will exchanged looks, Magnus imagined that their Parabatai bond helped when they didn't say anything. The stood silently for a few moments before Will huffed and Jem shrugged. They both turned their heads to look at the door, then at Magnus. With a sigh Jem stood up properly and walked towards the door.

"If I come back green, you can't laugh and I get to say 'I told you so"," Jem said and left.

Magnus shook his head, he didn't believe that Jem would come back green, mostly because Tessa still hadn't figured out how to change skin pigments, but she did know how to curse someone itchy for weeks. Will must have noticed Magnus move because he shot Magnus a look that conveyed years of frustration.

"You really shouldn't judge what you don't understand," Will finally said. He moved to the table next to the door that held a good supply of alcohol. "What's your poison?" he asked grabbing a bottle of amber liquid and pouring a glass almost to the top. He replaced the lid and looked at Magnus. "So?"

"What you're having will be fine," Magnus replied, looking forward to the first drop of alcohol he'd had since that disastrous party two weeks ago.

Will returned with the drinks and sat opposite Magnus on the couch. They sat in silence, nursing their drinks. Neither knowing what to say, neither wanting to break the silence first.

Magnus broke the silence. "It's not that I don't understand, I probably never will. It's that I gave up on my soulmate over a hundred years ago." He took a drink from his glass, watched as the liquid moved around the glass. "I envy you all, somehow the three of you make this work. You and Jem, you never argue over Tessa, and Tessa never seems to have to choose either of you."

Will looked surprised, Magnus couldn't blame him. Even he was surprised he said it. Will looked at his glass, the door, the intricate floor rug, everywhere but Magnus. When he did meet Magnus's gaze he looked sad.

"Jem and I spoke about it, just after I met Tessa. He came to my room, raving about this woman he met, his soulmate. I just laughed at him. And thought, 'I guess I should walk around and bump into a nice girl'. I just didn't realise that when I met her, she would already be taken." Will looked sad. He drank the rest of his glass in one gulp and sat up. "My mother told me stories of soulmate my whole life. I looked forward to meeting mine. I believed for ten minutes that she was the one… the one for me. Then Jem arrived and introduced us properly."

Magnus stood and took his and Will's glasses to be refilled. Another drink or two seemed like a good idea, with where the conversation was heading. "How did you figure it out? That Tessa was meant for both of you?" Magnus returned with the glasses, slightly fuller than last time with a clear liquid.

"My heart broke a little bit. Tessa must have noticed the look I knew I had on my face. She looked at Jem and me and she must have known how close we were." Will took a large gulp of his drink and sputtered a little. "Vodka is shite in London, for future reference." He took another gulp and put his glass on the table beside him. "Jem was more confused than I was. We'd never heard of two soulmate marks. Neither of us could believe it, but Tessa wasn't about to show us her mark."

"So, how did you confirm what she was saying?" Magnus interrupted. If he was being honest, his curiosity was going to be the death of him when it came to Shadowhunters. When these ones died, he decided, he wouldn't bother with any others unless he was getting paid.

"Sophie and Jessamine saw her mark. And then they both yelled at us for not believing her. As they said, 'why would fate only have one new woman show up in our lives if there was meant to be two?' Tessa didn't speak to either of us for two days. So, we spoke to each other. Fate decided that she was meant for both of us." He drained his glass and moved to get another one.

"Should you really have more?" Magnus found himself asking. He'd love to see the famous William Herondale drunk, but this was getting good and Magnus didn't want him passing out before he finished his story. Will would probably never be in the mood again to talk about this again.

"I can hold more than you think I can," he said when he returned to his seat, bringing the bottle with him.

"Well," Magnus said when Will didn't continue speaking, "how did that conversation go?"

"As bad as it sounds, Jem gets her first. With his reliance on Yin Fen his life will be short. When Tessa found out she locked herself in her room until Sophie convinced her not to waste what time she has with him. I don't know if Tessa found out about our discussion. But I'll be here for her when Jem passes. We both want Jem to have the best life he can before…" Will drifted off, not just his words but his eyes started to close.

Magnus sat in the library for a while longer, watching him sleep and listening to his breathing before leaving. He told Tessa and Jem he would be back in the morning when the adults had figured out what to do next.

Breaking from his memory because his ginger Einstein was meowing for his attention, he looked out at the view of New York from his window. He missed Will and Jem, they were good men. But, sometimes, having Tessa in his life was too much. He hoped when he met his soulmate that they were immortal. Watching Tessa go through Jem's Silent Brother ceremony and losing Will to old age made Magnus fear that he would get a mortal.

He didn't think he could survive losing someone who was meant to be his other half to old age. Not that he really wanted a soulmate at all.