So Magnus Bane has a thing for black-haired, blue-eyed boys. Him and anyone else who has met boys that look like that. And Alexander Lightwood looks like that.
Magnus knows Alec is gay or possibly bisexual by the way he nervously looks at all the guys who check him out, they way he anxiously sneaks peeks at Jace, and the way he just ignores a lot of the girls. Magnus is a bit busy freaking out about Isabelle and Barbara and Eugenia to really pay much attention to Alec, except to hit on him and help his friends.
When he shows up a week or so after Magnus healed him, he is pleasently surprised and agrees to meet him later that week. It's only afterwards, when he's looking again at the picture he has of Will, Tessa, Jem, Jessamine, Charlotte, and Henry, does he realize how much Will and Alec look alike. Then he remembers that Will's sister Cecily married Gabriel Lightwood and they had 3 children. Anna, Christopher, and Alexander. And now it was Alexander, Isabelle, and Maxwell.
And just like that, memories of two boys that had been locked away for such a long time came spilling out, like colors from a sunset, words from a book, tears from a pair of eyes.
Thomas was older, but Christopher skipped a year so that they could be in the same year at school. This was done because they were parabatai. Magnus had met a lot of parabatai in his years,(Will and Jem, Barbara and Eugenia, Anna and Jesse come to mind), but the friendship that they had was amazing.
He knew them as children, and the first thing they said to him was, "We're going to be eachothers pair of bar ties." The second was, "D'you know what bar ties are?" They were adorable dark-haired little boys who grew up into handsome young men, with an outrageous sense of humor. Magnus can remember that Christopher said the more scandalous jokes, while Thomas added his bit of dry humor. Well, Christopher's uncle was Will. And they both fell in love the summer that he spent in England, with Will and Tessa and Lucie and Cordelia. That summer, the boys came home from Idris Academy, and the Lightwoods came over to the Institute every night for dinner, and a lot of other families visited. Including Grace Cartwright and Lucinda Morgenstern.
Alec reminds Magnus of them, not just in looks, but in how the 3 boys loved. He thinks back to this one night when the moonlight spills on Alec's bare chest as they sleep peacefully in a hotel in St. Tropez. Alec loves Magnus a lot. Might even love me to ruins, he thinks.
That's dangerous- to love someone so much you might die for them. The night that Thomas died, he and Lucinda were hunting, and he stepped in front of her to shield her from a very nasty demon. No, he chides himself, Remember the good parts of them.
Like how they were both great brothers to Alexander, and great fighters. Like how they were the best swimmers he'd met. Like how they could shovel food into their mouths as if there was no tomorrow. Like how they wrote awfully bad poetry for Grace and Lucinda.
He glances down at Alec, and smiles, because Alec is all of those things. Then he frowns, because Alec hasn't given him any bad poetry yet.
Weeks later, they break up. And Magnus falls into a deep sleep. Because why would he want to be awake, when the man he thought he could give up his immortality for is not next to him? When he isn't even sure is Alec is alive, because Sebastian is loose. When he realizes he has too much food and sandalwood products just for the two of them? Why would he want to be conscious for all of these feelings? So he falls asleep.
That's a mistake.
He relives every bad moment, except now Alec is behind him, in front of him, everywhere. It's Alec he's kissing after bringing the French queen across a hot air balloon. It's Alec who begs him not to play awful music in Peru. It's Alec who is traveling the world now, who's talking to Camille, who's laughing into his mouth, who's convincing people to take pictures of him, who's considering taking his immortality, until it's not anymore.
Then it's Christopher pushing Anna out of the way of a demon, Thomas proclaiming to a dinner table that he will never eat mashed potatoes, Christopher teaching Alexander how to notch a bow, Thomas telling Eugenia that there's no one good enough for her, Christopher hugging Lucie as she cries about something, Thomas refusing to back down, and most of all, the both of them holding Cordelia, Lucie, James, and Matthew back the night that the Carstairs' house burned down, destroying many family records.
Well, in any occasion, it could also be Alec stepping into Christopher and Thomas's shoes and doing any of those things, because they're all Lightwoods and Lightwoods always are fierce, ruled by love, and above all, loyal to the Lightwood name.
(They also almost all die out of love, they die protecting loved ones in one way or another. He tries not to think of this as he, along with a great deal of Shadowhunters and Downworlders prepare to go to war against Sebastian and his army, and he sees Alec and Jace preparing to save Clary and destoy Sebastian, and avenge Max's death.)