“Well, there you have it,“ Magnus sighed dramatically, "the things I would do for you, Alexander Lightwood.”
or: when magnus proposes to alec, it doesn’t go as well as he had planned.
Mundane traditions were never Alec’s go-to’s but Magnus always entertained them because he found them endearing. The thing about mundanes was that they were so ignorant of the world that was devouring theirs completely, of demons and monsters, that they lived and loved carelessly and to the fullest and if anything, Magnus found that horribly wonderful.
So when it came to the stage in their lives where Magnus and Alec had come to terms with the unshakable fact that there would be no one in their lives but each other, Magnus looked for ways that were perfect enough in both their intention and presentation to ask Alec Lightwood to marry him. Magnus had watched innumerable episodes of reality tv shows and angsty movies alike to know by now at least seven different ways of proposing. There was the ‘propose at the top of a roller coaster’ option, but Alec was terrified of roller coasters though he’d never admit it, and the 'gather the whole family on a national holiday and set up a public spectacle’ option but for one, he’d seen that one go downhill and end up in public embarrassment too many times when the significant other said 'no’ and second, Alec wasn’t fond of public declarations of undying love. At the end, what was utterly them, and said 'stay-home date, good food and a private evening to themselves’ was the notorious hide-the-ring-in-dessert tradition. Alec loved it when Magnus cooked instead of magically conjured food and everything else was too uncharacteristic of them anyway, so Magnus planned the night of his life.