After Magnus is kidnapped by his father, Asmodeus, it takes Alec months to track down a demon reckless - or stupid - enough to help Magnus escape, to go against the Prince of Hell himself. But the price the monster asks…
“I… I have to think about it,” Alec stammers out, his mind reeling, his heart beating hard with dismay.
The demon grins. “I’ll be back tomorrow night, Shadowhunter, and I’ll expect your answer then…” And with that he disappears in a puff of pungent smoke.
Alec goes home. He goes home and he watches his sister and his parabatai squabble in the Ops Center, looking for clues leading to Valentine and his army - and to Magnus, too, because they promised Alec that they would help him get his lover back. But it’s been months now, months with no usable leads in sight, and Alec has to do something or it will be too late for Magnus, he fears.
And as he watches them, Alec realizes that, if he takes the bargain, if he gives the demon what he wants in exchange for Magnus’ freedom - he’ll never be able to come back here again. He couldn’t stand it.
Still, when the demon returns the following night, Alec says yes.
It’s a cold autumn evening in New York and Alec’s sitting on a bench in the park a stone throw away from Magnus’ loft, watching as the windows in it light up with the approaching darkness. Magnus is home. And there are Jace and Izzy with Clary and Simon in tow, rushing down the street, towards Magnus’…
Life seems to go on for the people Alec left behind. And it hurts. But it also fills him with… peace. This was his choice, and seeing Magnus returned safely, it was the right one. It was worth it.
His friends disappear inside Magnus’ building without paying Alec any mind, and he decides that it’s time to go.
Slowly, he gets up, leaning heavily on his cane, and stifles a groan as the pain in his joints flares up, aggravated by the cold that seeped into his bones. With his shoulders hunched inside his thick parka and his hat pulled low into his eyes, he shuffles away, invisible among the crowds. Just another plain old person among many.
Because that was the demon’s price, the price of Magnus’ salvation: fifty years of Alec’s life, freely given away in one night - a lifetime for a life saved.