If the party is really going to be Alec’s birthday then I want Alec and Magnus not being able to really interact because every time they get near each other another person gets in the way and Alec can’t really be rude because it’s his family and also Magnus’ friends and he can’t make a bad impression, so he goes out to the balcony when it’s just too much, and he takes a breath and Magnus stands next to him, not looking at him directly, and says softly ‘Happy birthday Alexander’ and Alec just throws himself at Magnus
Okay guys but Alec Lightwood is a very intimidating shadowhunter who is grumpy and serious most of the time. He is basically a giant and a bow and arrow expert. There is no doubt he can kill you a thousand different ways if you ever try to touch his family. But he is also this huge teddy bear who wears oversized sweatshirts with long sleeves and he is so sweet, caring and loving. He is a great parabatai and brother. He is sassy and he loves animals. He wakes up before his boyfriend to make him coffee but he is definitely not your bitch and I just love him so much for all of that.
What if, on the show, there was an episode where it was Alec’s birthday and like in the books, Magnus is the one to mention it. Imagine if Alec and Maryse get into an argument and Alec storms off upset and closes himself in his room. Imagine he slides down the wall onto the floor,hugging his knees. Out of nowhere, Magnus joins him. He doesn’t look at him or comfort him but instead simply says “happy birthday Alexander”. Alec doesn’t show any emotion; “thanks for remembering”. Then imagine that Alec just gently rests his head on Magnus’ shoulder and they sit in silence, comforting each other without words.