We all know that, as a warlock, Magnus is immortal, but Alec is not. What do tu think that will happen to them?

I dont have a clue, but Magnus loves him a lot so maybe he will kill himself when alec dies o he'll always remember him and will never be with anyone else o maybe he creates a spell to turn alec into an immortal being o himself into a human being. The other possibility is that both of them will die in the end of City Of Heavenly fuego :(

Maybe Magnus turns mortal because in City of Fallen Angels, Camille was saying something to Alec about Magnus' mortality.

SPOILER ALERT
Alec thinks about making Magnus mortal and Magnus figures it out and they break up...idk what happens siguiente I'm waiting for City of Heavinly Fire