In this one I'm going with Alex being a biological female who uses they/them pronouns. All characters are normal mortals.

There will be some Titanic references but don't worry if you don't get them. Enjoy!

"Hey Maggie, what're you wearing for the non-uniform on Friday?" Alex asked with a grin, sitting with Magnus on the bus home from school. Their hair, dyed violently red despite the school's objection, swung as they leaned over the seat to talk to Magnus, who was crammed into the seat next to his cousin Annabeth, who was engrossed in a book about classical architecture.

Magnus shrugged. "I haven't really thought about it, but isn't the theme cosplay? Perhaps we should go as a pair?"

Alex smirked evilly. "Did you misspeak, or is there something you want to tell me?" They teased. Realising what he'd said, Magnus' cheeks bloomed as red as Alex's hair.

"I said - I mean, I didn't -"

Alex laughed, though on the inside they shrunk a little. Don't be stupid, even if he liked you, you'd be the one to make a move.

"It's fine. Did you have any ideas? Hmm, do we go classic film or edgy comics? Or maybe something from YA..."

"I can't believe you convinced me to do this." Magnus groaned. It was the morning of the non-uniform day, and let's just say that the pair of them were a sight to behold. Magnus was clad in a white shirt and, according to Alex "you know, those old-fashioned trousers with shoulder-straps on them. The charming ancient ones," (at which point Magnus had begun to realise he was being made fun of and glared before seeing the funny side and dissolving into giggles), whilst Alex was rocking a "new money fancypants" dress and had styled their hair into curls. Vehement red curls.

"Aww, come on, it's fun, Jack." Alex grabbed his hand, and before Magnus could process that fact, began dragging him towards the school entrance.

"Rose?" Alex groaned as Magnus jabbed them in the side during maths. "I'm regretting this. It's kind of fun but I'm regretting this," they muttered. "That's payback. Anyway, um, I was wondering, do you want to, uh, go out for dinner later? You could come round to mine then we could go. Uncle Randolph'll still be at work." He stuttered, a blush slowly creeping up his cheeks.

Alex smiled slowly, letting the words sink in and frantically searching for the required sarcasm before the hopeless romantic side of them came out. "Are you inviting me on a date, Magnus Chase?"

Magnus but his lip, staring decidedly at question 6b in his textbook. "...If I said yes, would you agree to it?"

Alex couldn't help it; they grinned widely. "Of course I would!"

"You two, be quiet!" Called Ms. Freya.

Both looked down at their books again, hiding smiles.

"Stuff that dinner, this episode is great. Can we order food?" Magnus asked, looking down at Alex who was now shamelessly sprawled across his lap and most of the sofa after their accidental-on-purpose Shadowhunters marathon.

"That sounds yum. I'm not sure if I can be bothered to move, though." Alex laughed. "Hmm, I might like a Chinese..."

A thought popped into Magnus' head, and he cringed a little internally but spoke in a careful voice, "Where to, Miss?"

Alex gasped inside but instead curled their expression into a coy smile, "The one on Mall Street."

Magnus blinked. "Oh, ok th-"

Suddenly, the pressure on his lap lightened as Alex sat up. "To the stars, you gullible idiot," they murmured. And then their lips touched Magnus', and all else was forgotten.